Irt* '^. Y^ i*- *\fi/s. ^V*^ ■!^f •J.>'-'?? ^.;«V:. ■■ / '<5*W-f tf'i > ;>-:/?* ^2? .^fT -? I o^- ^ . • HARVARD UNIVERSITY. LIBRARY MUSEUM OF COMPARATIVE ZOOLOGY. io^ll. D~ ^^-vnl^T. I J%'^) jhd.^ijjJ2 I L 0, /^JD THE TEANSACTIONS OF THE LINNEAN SOCIETY OF LONDON. SECOND SERIES.— VOLUME VII. ZOOLOGY. LONDON: PRINTED BY TATLOK AND FRANCIS. BED LION COUET, FLEET STREET. SOLD AT THE SOCIETY'S APARTMENTS, BTJRLINGTON HOUSE; AND BY LONGMANS, GREEN, AND CO., PATERNOSTER-ROW. 1896-1900. .■A AUG 10 1900 C O N T E N T S. PART I.— December, 1896. I. Heport on a Collection of Cephalopoda from the Calcutta 31tiseum. By Edwin S. Goodrich, B.A., F.L.S., Assistant to the Linacre Professor of Comparative Anatomy, Oxford. (Plates 1-5.) pages 1-24 PART II.— May, 1897. II. Amphipoda from the Copenhagen Museum and other Sources. — Part I. By the Bev. Thomas R. R. Steering, 31. A., F.B.S., F.L.S. (Plates 6^14.) . . 25-45 PART III.— June, 1897. III. The Origin of the Corpus Callosum : a Comparative Study of the Hippocampal Begion of the Cerebrum of Marsupialia and certain Cheiroptera. By G. Elliot Smith, Jf.Z)., Ch.M. {Sydney), "James King" Besearch Scholar of the University of Sydney ; St. John's College, Cambridge. (Comtnunicated by Prof. G. B. Howes, Sec. Linn. Soc.) (Plates '15 &'16.) 47-69 PART IV.— Jlne, 1898. IV. On the Muscular Attachment of the Animal to its Shell in .some Fossil Cephalopoda {Ammonoidea) . By George Charles Crick, F.G.S., F.Z.S., of the British Museum {Natural History). {Communicated by the President, Dr. A. GOnther, M.A., F.B.S.) (Plates'^lT-SO.) 71-113 PART v.— October, 1898. V. Observations on the Structure and Morphology of the Cranial Nei'ves and Lateral Sense Organs of Fishes ; toith special reference to the Genus Gadus. By Erank J. Cole, Demonstrator of Zoology , University College, Liverpool. [Communicated by Prof W. A. Herdman, D.Sc, F.B.S.) (Plates 21-23.) .... ' 115-221 [ iv ] PAUT VI.— November, 1898. VI. A Contribution towards our Knowledge of the Morphology of the Oiols. By ^N.V.VYCY^\Y■v, A.L.S.,M.B.O.U. (Plates '24-29.) pages 223-275 PAET VII.— January, 1899. VII. The Brain in the Edentata. By G. Elliot Smith, M.B. (Sydney), St. John's College, Cambridge. {Communicated by Prof G. B. Howes, F.E.S., Sec. Linn. Soc.) (With 36 Illustrations in the Text.) 277-394 PART VIII.— May, 1899. VIII. Amphipoda from the Copenhagen Museum and other Sources. — Part II. By the Bev. Thomas R. E. Steering, 3LA., F.B.S., F.L.S. (Plates ""SO^.) 395-432 PART IX.— November, 1899. IX. On Fossil and Recent Lagomorpha. By C. I. Porsyth Major, M.B. {Com- municated by Prof G. B. Howes, Sec. Linn. Soc.) (Plates ''36-39.) . 133-520 PART X.— March, 1900. X. On the Genus Lemnalia, Gray; with an Account of the Branching -systems of the Order Alcyonacca. By Gilbert C. Bourne, M.A , F.L.S. , Fellow and Tutor of New College, Oxford; TJnicersity Lecturer in Comparative Anatomy. (Plates'40-42.) 521-538 PART XL— March, 1900. Titlepage, Contents, and Index 539-550 ERRATA. Page 180, line 'I'l from toj), tor Fierasfer dentulus read Ficrasfir dcntutas. Page 228, line 9 from bottom, for Pterohjsis read Pterylosis. Page 242, line 10 from bottom, for cops letjcotis, Temm., read Scops LEncoiis, Temm. Page 285, line 3 from bottom, for Ohlamdyoj^Jiorus read Chlamydophorus. Page 516, line 17 from toji, for J'lvhiyiis iniiiKjctisis, Kon., read Prolagus ceniiigensis, Kon. '/ (/ "T^ 2nd Ser. ZOOLOGY.] [VOL. VII. PART 1. THE ^^/l. ^ - 12^ TRANSACTIONS OF THE LINNEAN SOCIETY OF LONDON. REPORT ON A COLLECTION OF CEPHALOPODA FROM THE CALCUTTA MUSEUM. BY EDWIN S. GOODRICH, B.A., F.L.S., ASSISTANT TO THE LINACHK PROFESSOR OF COMPAKATIVK ANATOMY, OXFORD. LONDON: PRINTED FOR THE LINNEAN SOCIETY BY TAYLOR AND FRANCIS, RKD LION COURT, FLEET STREET. SOLD AT THE SOCIETY'S APARTMENTS, BURLINGTON-HOUSE, PICCADILLY, W., AND BY LONGMANS, GREEN, AND CO., PATERNOSTER-ROW. December 1896. TRANSACTIONS OF THE L I N N E A N SOCIETY. I. Report on a Collection of Cephalopoda from the Calcutta Iluseum. By Edwin S. Goodrich, B.A., F.L.S., Assistant to the Linacre Professor of Comp. Anatomy, Oxford. (Plates 1-5.) Eead 19th December, 1895. TiAST year Professor E. Ray Lankester received for examination from the Calcutta Museum a large collection of Cephalopods, which he kindly handed over to me to be identified. The work was carried on at the Oxford Museum and at the British Museum, Cromwell E-oad, and I must express my thanks to Dr. A. Glinther and Mr. E. A. Smith for placing the collections in the latter Institution at my disposal. The present collection is composed almost entirely of specimens captured during the voyages of H.M.S. 'Investigator.' It contains 162 specimens, belonging to 28 genera. Eleven new species are described, belonging to the genera Inioteuthis, Sepia, Loliolus, Sepioteuthis, Abralia, Cheiroteuthis, Histiopsis, Taonius, and Octopus. No new genus has been foimded ; but four genera included are new to the Indian region. Of these the genus Calliteuthis has been recorded from the Atlantic and Pacific regions ; the ^genus Histiopsis from the Atlantic ; and the genera Loliolus and Inioteuthis from the Pacific and Japanese regions. SECOND SERIES. — ZOOLOGY, VOL. VII. 1 2 MR. E. S. GOODEICH ON A COLLECTION OF DECAPODA MYOPSIDA. Family SEPIOLINI. Iniotetjthis maculosa, n. sp. (PI. 1. figs. 1, 2, & 3.) One specimen from the Anclamans, and another from the Persian GuK ; both females. The principal measurements of the first are * : — Length of mautle (lower surface) TS centim. Breadth „ '95 „ „ . attachmeut to neck '4 „ ,, between fins '8 ,, J, across eyes '7 „ „ of fin '4 „ Length of fin-attachment '4 „ „ from extremity of mantle to tip of dorsal arm . 2'4 ,, Length of dorsal arm '8 „ „ dorso-lateral arm "10 „ „ ventro-lateral „ '11 >, „ ventral „ '7 » „ tentacular „ 2'1 „ „ „ club '5 „ The mantle is rounded at its apex. The round fins are attached about halfway up the mantle. The band uniting the mantle to the neck is narrower than in In. Morsei. The funnel has a small opening, and a wide base on which are l-shaped sockets. The two muscular bands which unite the base of the funnel above the sockets to the head are less prominent than in Sejnola oi' In. Morsei. There are glandular pads and a small valve inside the funnel. The edge of the bviccal membrane is notched, but the lobes are not distinctly marked. The first two pairs of arms are rounded ; the ventro-lateral arms are slightly keeled ; the ventral arms are provided with a well-developed keel on the upper edge. They all bear two rows of round suckers, obliquely set on slender stalks rising from a swollen base. The opening of the sucker is wide ; the horny ring has an ornamented surface and a smooth edge. The tentacular arms are flattened, and a groove runs down tbe inner surface. The club is of great Iciigth, slightly enlarged, provided with a lateral membrane on both sides, and a large niimber of minute suckers in eight rows. Each sucker is nearly hemi- spherical, set obliquely on a long slender stalk (fig. 3). The papillary area of the horny ring is wide, and the edge armed with alioiit 15 teeth (fig. 2). The ground-colour of the first individual is pale brownish yellow, inclining to orange * In the following descriptions the terms " upper " and " lower " are used to denote the surfaces generally called " dorsal " and " ventral ; " since, strictly speaking, they do not correspond to the morphological dorsal and ventral surfaces. CEPHALOPODA PEOM THE CALCUTTA MUSEUM. 3 on the arms and upper surface of the mantle. Scattered over the mantle, more especially on the lower surface, are large hrown chromatophores (fig. 1) ; similar clu'omatophores are seen on the upper surface of the fins, and on the head and arms. There is a con- spicuous row of five between the eyes on the upper surface of the head. The second specimen is of a duller tint and less well preserved. This species appears to he more closely related to Iniotenthls japoiiica (Tilesius, MS.), Verrill, which also has two rows of suckers on the arms, than to In. Morsel, Verrill, which has foiu*. Inioteuthis Moksei, Verrill. Seven specimens from the Andamans have been placed in this species. FamUy SEPIAEII, Stp. Subfamily Sepiadarii, Stp. Sepiadarium Kochii, Stp. FoLU' specimens, all female. One from off the south coast of Ceylon, lat. 6° 6' 30" N., long. 81° 23' E., from a depth of 32 fathoms. The other three from the Andamans. Sepia singaporensis, Pfeff'er. One female specimen from Singapore. Sepia aculeata, von Hasselt. Ten specimens apj)ear to belong to this species. One from the Irawaddy delta, at a depth of 20 fathoms ; four from Port Blair, and five from the Andaman Sea. Sepia singalensis, n. sp. (PI. 1. figs. 4, 5, 6, 7, & 8.) Two male specimens ; the first from Colombo, the second from off Point Galle (?). The principal measurements of the former are : — Length of mantle (above) 16 ceutim. (below) 14-1 „ from „ apex to mouth . . . 17'4. „ Breadth of „ at origin of fins . . . 4'9 „ „ » halfway 6-2 „ fin 1-2 )> Length of dorsal arm 7 „ „ dorso-lateral arm 6"5 „ „ ventro-lateral „ 6"3 „ „ ventral „ Q-7 „ „ tentacular „ 12'7 „ „ „ club 3-1 „ pen 15'5 „ Breadth of „ 4-8 „ 1* 4, ME. E. S. GOODEICH ON A COLLECTION OF The mantle is of a narrow oval shape ; the strong fins arise a little way below the mantle-margin, and do not join at the ajiex (fig. 4). The siphon is thick-walled, with a somewhat crescentic opening; it does not reach to the junction of the ventral arms. The arms have broad compressed bases (especially the ventral arms, which are 23 mm. broad), without well-developed keels. The inner surfaces, bounded on either side by narrow lateral membranes, bear four rows of moderate-sized suckers, largest on the lateral arms, where they attain a diameter of 2 mm. On the distal half of the arms the suckers become extremely small. The horny ring of the arm-suckers has a narrow paj)illary area, and a margin smooth on the proximal two-thirds of its circumference, and armed with very irregular teeth on the distal third (fig. 8). The stem of the tentacle is compressed, forming a sharp edge on the outer surface. The club is furnished as usual with a wide keel springing from the upper surface. Svickers of very unequal size are jjlaced in four rows on the proximal region ; the largest attain a width of 4 mm. in the two central rows, and are provided with smooth horny rings. The suckers diminish rapidly in size at either end ; these and the suckers of the outer rows have horny rings armed all round with numerous sharp teeth (fig. 7). In the distal region the small suckers are closely packed in six or seven rows, and near the extreme apex two suckers stand out from the rest on the upper margin as if utilized for some special purpose (an arrangement I have noticed in Sepia officinalis). The buccal membrane has seven lobes provided with a few suckers, the horny rings of which closely resemble those of the arm-suckers. A small Aveb is developed at the bases of the arms except of the ventral jiair. The mandibles are shown in fig. 6. The long oval pen of this Sepia is very remarkable (fig. 4). Above, the rough calcareous surface raised in three slight ridges narrows anteriorly, and is bounded on either side by a broad expanse of the chitinous margin {ch.m.) (in places about 1 cm. broad). Below, the striated area formed by the loculi reaches far up (loc), and is marked in the centre by a longitudinal groove. The margin of the inner cone is produced forwards and reflected over the posterior loculi, to which it is closely applied (i.e.). The apical spine has unfortunately been broken off ; it appears to have been small. It is not without hesitation that I have placed these specimens in a new species, as they closely resemble Sepia Bouxii, d'Orb., described in d'Orbigny and F^russac's monograph from the Indian seas (5). There are, however, several characters in which the two species differ. "Whereas 5. Mouxii is of a " forme generale racourcie," has very wide fins, and toothed rings to all the suckers of the tentacular club, S. singalensis is of narrow shape, with moderate fins, and smooth rings on the largest suckers. On the other hand, their pens are remarkably similar. The ground-colour of the best specimen is pale brown, speckled vnih. slate-coloured chromatophores on the lower surface, and conspicuously striped with broad dark bands on the ixpper surface of the mantle, head, and arms. The hectocotylized region is short and sitviated about halfway up the left ventral arm. CEPHALOPODA FBOM THE CALCUTTA MUSEUM. 5 At this point the suckers are small and resting on elevated transverse ridges. Scattered about the siphon of one specimen are spermatophores, conspicuous for the covering of black adhesive substance at the base (fig. 5). Sepiella inermis (van Hasselt, MS.). Among the 25 specimens referred to this species there is great variation as to general appearance, shape, width of the fins, and details of the structure of the pen. Neverthe- less I have not been able to distinguish any modifications of specific importance. The differences in the soft parts seem to be due to varied preservation. Six specimens were captured near Madras, three near Bombay, five at Sandlieads, one in the Chilka Bight, one at Mergui, two at Singapore, two at Penang, and five off the Ganjam coast at a depth of 10 fathoms. PamHy LOLIGINEI. Sepioteuthis indica, n. sp. fPl. 1. figs. 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, & 19.) Although the nine specimens in the collection belonging to the genus Sepioteuthis differ considerably in size and colour, I refer them all to one species. The best- preserved individuals are of a pale brownish-yellow ground-colour, sprinkled with slate- coloured chromatophores, very thickly on the upper surface of the mantle, head, and arms, more sparsely on the lower surface. Seven specimens come from the Andamans, and two from Singapore. Below are the principal measurements of a large male and of a large female : — Large Male. Large Female, centim. centim. Length of mantle (lower surface) .... 15'5 18"3 Breadth „ near margin 5"1 5'9 „ „ halfway 5-1 6*1 „ fin 7 cm. from mantle-edge . . . 2'9 2'9 ir, £ ii 1 .1 12-5 cm. from") n c- „ „ 10 cm. trom mantle-edge ... 3 \ o'b mantle-edge J Length of dorsal arm 5"2 5"5 „ dorso-lateral arm 6"3 6*5 „ ventro-lateral „ 8 9 „ ventral „ 7-4 8"6 „ tentacular „ 13'5 15 club 5-2 Q-7 Length of pen . . . ^ \2> cm. $ 20"5 cm. 12-7 cm. Breadth of pen . . . 2"4 4 3 Prom the outline figure given (fig. 9) it Tvdll seen that the fins are perfectly rounded, while the mantle from about halfway tapers to a blunt point ; the whole forming an almost perfect oval. In this respect this species resembles 8. BlaiiwilUana, Per., and S. mauritiana, Q. & G. The fins begin "35 cm. from the margin of the mantle and join 6 MK. E, S. GOODRICH ON A COLLECTION OF behind at the aj)ex. The siplion presents no peculiarity. The olfactory fold below the eye is prominent, undulating, and with its two extremities turned forwards (fig. 13). The buccal membrane is large (in one specimen extending 2 cm, beyond the mandibles), and provided with seven lobes bearing suckers. The horny ring of the latter is armed on its distal border with strong teeth (fig. 15). The jaws are shown in fig. 14. Adhering to the buccal membrane of tliis specimen (a large female) are spermatophores very similar to those oi LolUjo Indica (PI. 2. fig. 28), but slightly thicker. The powerful arms are provided on both edges of the inner surface with a lateral membrane, strengthened by transverse muscular ridges springing fi'om the base of the suckers. This membrane is especially well-developed on the lower edge oE the second or dorso-lateral arm. A median outer keel is developed along the dorsal and ventro-lateral arms ; a lateral keel on the outer lower edge of the dorso-lateral arm ; and two lateral keels on the ventral arms, the upper one being large and membranous. The suckers, closely set in two rows, are of moderate size, largest on the dorso-lateral arms, where they attain a diameter of -35 cm. The horny ring is armed with from 20 to 28 strong teeth (generally 21-22), rather larger on the distal border (fig. 17). The stem of the tentacular arm is thick, and flattened near the base (13 mm. broad aboixt 5 cm. from the base in the large female already mentioned), from the inner edge of which springs a membrane reaching down below the buccal membrane. The club is wide, provided with a keel on its outer edge and with a membrane on either side, and bears four rows of suckers of tmequal size. The largest suckers, situated towards the centre of the club, reach a diameter of 5 mm. ; their horny rings are armed usually with 15 teeth (figs. 18, 19) (sometimes with 16-18 teeth). The smaller distal and proximal suckers and the outer rows of suckers usually have 17 large sharp teeth on the distal border. At the tip of the club is a slightly spoon-shaped expansion, on which the suckers are modified, and arranged in two rows on either side enclosing a space (fig. 12). These suckers are highly specialized, being small, flat, and very short-stalked ; the papillary area of the horny ring is very wide and beset with rows of conical teeth reaching the margin (figs. 11 & 12). Such a special group of suckers constitute what I shall call the apical set, an arrangement which has not, so far as I am aware, been noticed by previous observers in the Myopsida. It is found in both sexes, and reminds us strongly of a somewhat similar group in Onychotenthls; the apical set of suckers, perhaps, forms a sort of " connective appai^atus." It occurs also in Loligo JPealei and L. indica ; on the other hand, it appears to be absent in L. marmora and in the genus Loliolus. ^ In the male the hectocotylized left ventral arm is modified from about the 23rd pair of suckers to the tip. In this region (fig. 16) the suckers are reduced to conical papillge. The right arm, as noticed in other species by Steenstrup (7), is also slightly modified, the suckers near the tip being unusually small. The pen is very like that of SejjioteutJns Blainvilliana, Fer., thin, lanceolate, convex above, with a strong, raised, convex ridge down the middle (fig. 10). It is often very difiicult to distinguish between the various species of this genus described by authors. Sepioteuthis Blainvilliana, Fer., and S. nlauritiana, Q. & G. (5), CEPHALOPODA FEOM THE CALCUTTA MUSEUM. '7 •seem to be tlie nearest allies of this new species. Prom the former it is distinguished by the lesser number of teeth on the homy rings of the arm and tentacular suckers, by the presence of suckers on the buccal membrane, and by the undulation of the olfactory ■.crest (?). From the latter, S. maurltiana, it is distinguished by the lesser number of teeth on the horny ring of the slickers and by the sliape of the pen. LOLIGO INDICA, Pfeffer. (PI. 2. figs. 20, 21, 22, 23, 24, 25, 26, 27, & 28.) To this species arc referred eight specimens from Mergui, one from Camorta Harbour, one from Daley Sandheads (1887), and two from the mouth of the Mutlah River; also, with some hesitation, a large female from the Ohilka Bight. The first 12 specimens differ little in size ; below are the measurements of a male and of the large female mentioned above : — 6- ?• ecntim. ceutim. Length of mantle (npper surface) 9"1 14 Breadth „ at beginning of tins .... \Q 3 Length of fin-attachment 5 7"6 Breadth of fins combined -i'S 7"65 Length of pen of a smaller ^ , 6'6 centira., breadth ] -2 centim. „ „ the large 2 , li centim., breadth 2-7 ceutim. I feel obliged to go into some detail concerning this species, since the figures and descriptions published by Mr. Hoyle of the ' Challenger ' specimens (i) differ widely from Dr. Pfeffer's original description (6). Concerning the horny ring of the suckers of the arms, Pfeffer says, " Armringe mit 6 ziemlich grad viereckigen Zabnen ; darauf folgt die erhabene Leistc, die vorn nocli jederseits cine Einkerbung als Paxdiment eines Zahnes zeigt." This hardly agrees with Hoyle's figures, but corresponds exactly to my figure of the horny ring of the female (fig. 26). With regard to the horny ring of the suckers of the arms, I find that there is a well- marked sexual difference, for in the males these rings are armed with from 9 to 11 rounded teeth (fig. 20). Again, concerning the horny ring of the tentacular suckers, Pfeffer says, " Grosse Tentakelringe mit etwa 21 spitz dreieckigen Zahnen, deren Basis schmaler ist, als die Zwischenraume." While this description differs much from Hoyle's figures, it agrees entirely with what I find (fig. 27). iVlthough 21 is the usual number of teeth in these specimens, there are sometimes as few as 15 in the large female. Pig. 24 shows the horny ring armed with G strong teeth from one of the very small distal suckers of the ckib ; while fig. 25 represents a portion of the horny ring from one of the suckers of the apical set at the tip of the club (cfr. Sepiotetdhis, j). 0). The lobes of the buccal membrane are provided with small toothed suckers, the horny ring of which is shown in fig. 21. I figure also a club-shaped spermatophore removed from the buccal membrane (fig. 28). '8 ME. E. S. GOODEICH ON A COLLECTION OF The hectocotylized arm of the male is strongly modified. On its proximal half are two rows of small suckers (fig. 22) ; on the outside of these the upper edge of the arm is drawn out into a wide thick flap (fig. 22, Ji.). On the distal half of the arm the suckers are reduced to rounded projections {m.s. fig. 23) which bend over a groove. The outer and upper edge of the arm is developed into a lateral membrane of considerable width {l.m. fig. 23). LoLiOLrs iNVESTiGATOKis, n. sp. (PI. 2. figs. 29, 30, 31, 32, 33, 34, 35, 36, & 37.) Nine specimens, some of which are much mutilated. The specimen figured and one other come from the Mutlah River, five from the Ye River, one from Mergui, and one from Sangor. They vary considerably in size ; the following are the principal measurements taken on the specimen figiu'ed, a male of average size : — Lengtli of mantle (upper surface) .... „ from apex of mantle to base of arms Breadth of mantle near edge „ across eyes .... „ „ combined fins Length of attachment of fins „ dorsal arm dorso-latcral arm ventro-lateral „ ventral „ tentacular „ 3'5 centim 4 1-3 1-35 2-9 2-1 •8 1-6 2-] 1-8 3-3 , The mantle is of conical shape, with a roimded apex ; its margin projects on the upper surface into a small point above the neck, and below on either side of the funnel (figs. 29 & 30). The fins have rounded anterior and lateral edges ; the two together form a heart-like figure. They join and are continued beyond the mantle apex. The head is large and provided with a transverse olfactory crest below the eye. The siphon possesses a valve, and muscular bridles hidden below the skin. The three dorsal pairs of arms bear on their outer sui'face a median keel, especially well-developed on the 3rd pair. The ventral arms are somewhat square in section, and both the outer edges are drawn out into lateral keels. Small lateral membranes spring from the inner surface on the ujiperside of the 1st and 2nd pairs of arms, and on both sides of the 3rd and 4th pairs of arms. The suckers, in two rows, are obliquely set on their stalks (fig. 36) ; the horny ring is provided with three large blunt teeth (fig. 37). The tentacular arms enlarge distally into small c]u.bs, bearing an outer keel and four rows of suckers. The horny ring of these is armed with sharp teeth on its distal border (fig. 35). A few small suckers are situated on the seven lobes of the buccal membrane ; their horny ring strongly resembles that of the tentacular suckers, but there are only from four to six large teeth. The mandibles are rather weak (fig. 34). The lower mandible has a sharp, hard, tooth-like point and a small basal tooth (b.t. fig. 34 b). CEPHALOPODA FROM THE CALCUTTA MUSEUM. 9 The pen is lanceolate; narrow anteriorly, it broadens out to a thin blade behind (fig. 31). In the male the left ventral hectocotylized arm is somewhat sickle-shaped (figs. 29 & 32). The upper outer edge is developed into a wide lateral membrane [l.m. fig. 33), and the suckers are more modified than in Steenstrup's species (7), the upper row being reduced to mere papillae, and the lower row having almost entirely disappeared (fig. 33). OIGOPSIDA. Family ONYCHII. Abralia andamanica, n. sp. (PL 2. figs. 38, 39, 40, 41, 42, 43, 44, & 45.) Three specimens, captured at a depth of from 188 to 320 fathoms in the Andaman Sea, belong to this species. The following are the measurements of the largest specimen, a female (fig. 38) : — Length of the mantle (lower surface) 3"8 centim. „ from mantle-edge to base of arms . . . 1"2 „ ,, of attachment of fins 2'3 „ „ from mantle-ajDcx to angle of fin ... 2*7 ,, Bi-eadtli of combined fins 3'4 „ Length of dorsal arm 1-7 „ „ dorso-lateral arm 2 „ „ ventro-lateral „ 1*8 „ „ ventral „ 2 „ „ tentacular „ 4 „ club -8 „ Length of pen of a male, 2'4 centim., breadth 35 centim. The mantle is nearly conical, tapering gradually to the apex. At the free edge there is no pronounced dorsal point, but there is a small projection on each side of the funnel (figs. 38 & 39). The fins, rhomboidal in shape, reach about halfway np the mantle ; their posterior edge is slightly concave, their anterior convex and more rounded. The head is large, and fits closely on to the edge of the mantle. At the edge of the eyelid is a rudimentary sinus. On each side of the neck are two olfactory crests, the smallest being nearest the siphon. There is a well-developed valve in the funnel ; and the socket at the base of the latter is l-shaped. The buccal membrane has 8 lobes ; its nner surface is covered with pajiilte of considerable size. The first and second pairs of arms have a median external keel, and a small lateral membrane on the upper edge. The third, or ventro-lateral, pair has a large membranous keel {k, fig. 38), and a membrane along the lower edge. The ventral arms have the outer and upper edge drawn out into a lateral keel. All these arms bear two row^s of hooks for about three fourths of their length, and two rows of suckers on the distal quarter. On the ventral arm, for instance, 14 hooks and SECOND SERIES. — ZOOLOGY, VOL. VII, 2 10 ME. E. S. GOODEICH ON A COLLECTION OF 12 suckers can be counted. These suckers are very obliquely set on short stalks (figs. 42 & 43), and of a compressed conical shape. The horny ring is studded with tectli, and the margin is armed with small teeth on the proximal side and large blunt teeth on the distal side. The tentacular arms are scarcely at all enlarged to form the clubs (figs. 38 & 40). Each club bears a small keel externally, three hooks along the lower edge of the internal surface {Ji), and above these two rows of suckers. Beyond the hooks on the distal region small suckers are arranged in four rows. The horny ring of the suckers is furnished with small teeth round its margin (figs. 44, 45). Near the base of the club a set of three small short-stalked suckers alternating with three tubercles forms a connective apparatus {c. app. fig. 40). ^i§. 41 (a & b) shows the pen of a small male, the mantle of which is 3 cm. long ; it is lanceolate, with a strong median ridge. This specimen has a large bundle of sperma- toj^hores in the mantle-cavity. In colour the female is of j)ale yellowish-brown tinge, inclining to orange on the upper surface, covered with dark purjile-brown chromatophores, most numerous on the upper surface of the mantle, head, and arms, and on the buccal membrane. The male is paler, the chromatophores being less numerous. Both sexes are provided with a very large number of small dark tubercles, generally showing a white opaque lens in the centre, distributed over the lower surface of the mantle, head, funnel, and ventral arms (tig. 38). These tubercles, no doubt luminous or phosphorescent organs, are evenly scattered over the lower surface of the mantle ; on the siphon they are situated in six irregular longitudinal series ; on the head there is a row round the lower half of each eye and nine rows between these. Three rows extend on to the base of the ventral arms, but only two are continued to their extremities. Abralia lineata, u. sp. (PI. 3. figs. 46, 47, 48, 49, & 50.) Two specimens ; one, a male, taken at a depth of 265 fathoms in the Andaman Sea, the other, a female, at a depth of from 90 to 100 fathoms off the Ganjam coast. The principal measurements of the first specimen, which is the one figured, are given below : — Length of the mantle (upper surface) 1"5 centim. ,, „ (lower surface) 1"3 „ „ from mantle-apex to base of arms ... 2 „ ,, of attachment of fin "8 „ „ of jjosterior border of fin '9 „ Breadth of mantle "6 „ ,, combined fins 1'5 ,, Length of dorsal arm ■" ,, „ dorso-lateral arm I'O , „ ventro-lateral „ "9 „ ., ventral ,, I'l „ ,, tentacular „ 1"6 ,, CEPHALOPODA PBOM THE CALCUTTA MUSEUJM, 11' The sliort mantle tapers to a sharp point. The fins are rhomhoidal, with anterior rounded horder and nearly straight posterior border ; they extend forwards more than halfway up the mantle beyond the point of attachment. The head, of about the same width as the mantle, is provided with large eyes, and fits less closely on to the mantle than in the preceding species (this may be due to differences in preservation). A small olfactory crest is situated behind the eye. The funnel has a valve, two well-marked bridles, and l-shaped sockets. The buccal membrane has 8 lobes. The three dorsal pairs of arms are rounded proximally and slightly keeled distally. The ventral arms have a lateral membrane on the upper side. Two rows of hooks are borne by all the arms along almost their entire length. The ventral arms appear to bear no suckers at all distally, but their tips are swollen, and pi'ovidedin both sexes with three large convex pigmented organs forming a sort of club. These swellings are probably phosphorescent organs ; they correspond exactly to the modified arms described by Pfeffer in Enoploteuthis Iloylel, Pfelfer, and considered by him to be due to hectocotyli- zation. The other arms bear, near their extremity, a small number of minute suckers, the horny ring of which is armed on the distal margin with large teeth (fig. 49). The tentacular arm is slightly expanded to form a club, bearing in the middle region four hooks on the lower side, and three hooks alternating with suckers on the upper side (fig. 48). Beyond these are four rows of small suckers, with a wide ornamented papillary area and a smooth margin (fig. 50). At the base of the club is situated the connective apparatus of four suckers and tubercles (, Length of pen 40*4 „ Breadth „ "75 „ The colour of this specimen in spirit is of a dull purplish-brown, lighter and yellower on the lower surface, darker and inclining to heliotroije and blue on the uppper surface of the mantle, head, and on the outer surface of the arms. The buccal membrane, inner surface of the arms and suckers are paler. The mantle, as seen in the figure from the ventral surface, tapers gradually until the middle of the fin, whei-e it is very narrow ; it then enlarges slightly, and is produced beyond the fin at its apex {ap.2)rol.) very much as in Cheiroteuthis Ficteti, a species CEPHALOPODA FEOM THE CALCUTTA MUSEUJM. 13 admirably described by M. Joubin (2). This apical jirolongation of the mantle is shorter than in the latter species, and moreover is provided with a lateral fin on each side {ap-f.), a character which distinguishes the present species at once from any hitherto described. The mantle is laterally compressed, forming slight median longitudinal upper and lower ridges. Dorsally the mantle-edge is produced in a point above the neck ; below it is raised opposite the funnel. The fins are wide, the outlines of the right and left together forming an almost perfect circle {f, fig. 51). The funnel, provided with a large internal valve, is fixed to the head without distinct bridles, and at its posterior edge carries two sockets, each possessing two prominent lobes fitting into corresponding depressions in the mantle (fig. 56, a Sc h). The head is small ; the eyes moderately large and without sinus. About halfway between each eye and the attachment of the si2)hon is an olfactory jjapilla {olf.p.), about 2 mm. in length. The buccal membrane is well developed, with seven lobes and ridges. The mandibles are very sharp (fig. 54, a & h) ; the ujiper mandible has a basal tooth on either side {bt., fig. 54^), corresponding to which are small teeth on the lower mandible. The radula consists of seven rows of teeth (fig. 57), closely resembling those of C. Picteti, Joubin (2). All the arms are somewhat square in section, and are provided along the upper and outer edge with a membrane very narrow in the first two pairs, absent in the third, and very broad in the fourth (;«). The third and fourth pairs have narrow membranes along the lower and outer edge *. Two rows of small suckers are placed rather far apart along each arm (rather more closely set on the dorsal than on the ventral arms). Each sucker is obliquely set on a slender stalk, and has a narrow opening, the horny ring of which is armed on the distal side with square teeth (fig. 55). The soft rim of the sucker is more or less raised uj) into a peak above the toothed horny margin (fig. 55). On the ventral arms, at the base of the outer row of suckers are convex pigmented patches, no doubt similar to the " vesicules refringentes " described by Joubin in Ch. Veranyi (3). The tentacular arms, which have unfortunately lost their clubs, are long and slender, bearing at intervals the modified flattened suckers characteristic of the genus. The pen was somewhat injured owing to the contraction of the mantle. It is very long and narrow (fig. 52, a & h) ; the hollow cone reaches halfway up and opens by an oblique aperture. Diagrams of transverse sections of the cone and of the anterior region are given in figure 53, a & h. The pen thus closely resembles that of Ch. lacertosa, described by Verrill (9), and of Ch. Picteti ; yet the portion in front of the cone is not tubular, as figured by Joubin for the latter species Ch. Vei'anyi, on the other hand, has hitherto been described, by d'Orbigny and Ferussac (5), and by Verany (8), as possessing a pen flattened and expanded at both ends. On examining a siDecimen from the Mediterranean, I find, however, that its pen resembles in every essential that of Ch. macrosoma here figured ; in the case of the works referred to, the artist probably flattened out the slender cone before drawing it. * These membranes correspond rather to the keels in other forms, as they do not spring directly from the sucker-bearing surface of the arm. 14 ME. E. S. GOODRICH ON A COLLECTION OF Of the four species * of Cheiroteuthis hitherto known, two come from the Atlantic, one from the Mediterranean, and one from Aniboyna. In general shajoe and size the present species approaches most nearly the latter, Ch. Picteti ; yet it differs from it in the possession of a fin along the apical region of the mantle, in the beak, horny ring of the suckers, socket at the base of the siphon, and pen. f Cheiroteuthis pellucida, n. sp. (PI. 4. figs. 58, 59, 60, & 61.) This small specimen, cajitured at a depth of 922 fathoms off the Vizagapatam coast, lat. 16" 11' 15" N., long. 82° 30' 30" E., was brought up alive on deck, when it appeared transparent, with dark purple chromatophores. In spirit it is still remarkably trans- parent, and the chromatophores (not represented in fig. 58) are very large and few in nixmber, scattered at wide intervals over the body, fins, and arms. Tlie principal measurements are as follows : — Length of the mantle (lower surface) 4*8 eentim. Breadth „ '8 „ Length „ to sudden constriction . . 2'G „ „ „ beyond fin 'G ,, ,, of fin-attachment 2'1 ., Breadth of fin 1-8 Length from mantle-edge to base of arms . . . 2.2 „ Breadth across eyes -7 „ Length of dorsal arm 1-4 „ „ dorso-lateral arm 1'8 „ „ ventro-lateral „ 2"3 „ „ ventral „ 4'5 „ ,, tentacular ,, 8 „ >, ,> club 3 In general appearance this interesting little Cheiroteuthis reminds us strongly of Doratopsis vermiciilaris (Riippell) by its long and almost cylindrical mantle with a narrow apex, its long thick neck, and the great disparity in size between the ventral and remaining three pairs of arms. The mantle, as already mentioned, is nearly cylindrical until it suddenly narrows down in the region of the fins to a narrow straight prolongation, which extends beyond the fins, forming a rounded spine (fig. 58). The fins themselves are broad and rounded (/), but the outline is less circular than in the preceding species. Dorsally the mantle projects over the neck in a small point. The fiinnel is sharply recurved at its apex, and provided internally with a broad valve produced and thickened at the sides. The socket of attachment is shown in fig. 59. The head is hardly wider than the neck ; the eyes are somewhat prominent. Between these and the siphon are two olfactory papillae (olf.p.). The buccal membrane is furnished with seven well-marked ridges and lobes. Beyond the eyes the head narrows considerably, and enlarges again to support the * M. Joubin has lately described a new species from the Atlantic (4). CEPHALOPODA EfiOM THE CALCUTTA MUSEUM. 15 arms. The three small and dorsal pairs of arms bear two rows of suckers, aud have no lateral membrane. The large ventral arms have a membrane on the upper side ; toward, the base they bear two rows of suckers, but about halfway up the suckers come to alternate in so nearly the same sti*aight line that there appeal's here to be only one row. The horny ring of the suckers (fig. 60) is armed mth rounded teeth on the proximal, and powerful sharp teeth on its distal side. The tentacular arms are comparatively short, and provided at intervals with numerous flattened suckers. The long clubs bear four rows of small suckers, the outer row of which has the longest stalks. Round the margin of the club is a ribbed lateral membrane ; the apex ends in thickened, deeply pigmented, aud somewhat spoon-shaped knob. The horny ring of the suckers has a wide papillary area bearing sharp teeth, and characteristically notched on its distal border ; the proximal margin of the ring is smooth, the distal margin armed with powerful sharp teeth (fig. 61). I have not dissected out the pen ; it appears to closely resemble that of the foregoing species. Although, as the description shows, this specimen closely resembles JDoratopsis, yet the structui'e of the tentacular arms shows that it undoubtedly belongs to the genus Cheiroteutliis. HiSTiOPSis HoTLEi, n. sp. (PI. 4. figs. 62, 63, 64, 65, 66, 67, 68, 69, 70, & 71.) One specimen captured near the Andamans, at a depth of 190 fathoms. Length of mantle to notch between fins (upper surface) . 2"2 ceutim. „ „ to apex (lower surface) 1-9 „ Breadth ,, 1'2 ,, Length of fin-attachment to posterior notch "6 „ ,, fin beyond mantle-apex -'i ,, „ combined fins 1"3 „ „ dorsal arm (riglit) 3"5 centim. (left) 3"3 centim. „ dorso-lateral arm „ 3*4- „ „ 3*7 „ „ ventro-lateral ,, „ 3-1 „ „ 3'-i „ „ ventral „ „ 3 „ „ 3-2 „ „ tentacular „ „ 7 „ „ pen 2'1 centim. Breadth of ,, -6 „ The mantle swells out slightly midway, then tapers to a blunt point (figs. 62 & 66), Dorsally it projects above the neck ; the lower m.argin is nearly straight. The fins are rounded, joined distally above the mantle-apex, beyond which they project. The funnel is strongly recurved {si., fig. 68); the two lips which bound its aperture are so applied to each other as to leave a narrow U -shaped opening. The sockets at the base of the funnel are I -shaped {so.) ; two small bridles bind it to the head. Inside we find a small valve prolonged into the upper portion of the ' funnel-organ,' which covers the upper or attached Avall of the siphon, and into which fit two rounded flaps fixed on either side to the lower or free wall of the siphon. The whole arrangement closely 16 ME. E. S. GOODEICH ON A COLLECTION OF resembles that described and figvired below in Taonius abysslcola. Mr. Hoyle makes no mention of the ' funnel-organ' in liis species (i). The head is wide and sharply marked off from the narrow neck. Below each eye is an olfactory papilla {plf.j}., fig. 64). The eyes are large, with widely open eyelids (figs. 62 & 64) ; the left eye is injured and protrudes from the eyelid, it has been restored in the figure. The arms, which differ somewhat in length on the right and left sides, appear to be in the following order of length : 2, 1, 3, 4. Unlike H. atlantlca of Hoyle, the web at the base of the arm is quite rudimentary (fig. 63). The small suckers, placed in two rows on all the arms, are of a peculiar conical shape (figs. 69 & 70), with a wide opening furnished with a narrow horny ring armed round its margin with small sharp teeth. The left and only complete tentacle enlarges at its extremity into a small club (figs. 62 & 65), bearing four regular rows of small suckers on its distal half, and as many as six irregular rows on its proximal half. At the widest region of the club the central suckers attain a large size (fig. 65). They have round shallow cups, set almost straight on short thick stalks (fig. 67) ; the margin of the horny ring is armed with numerous long straight pointed teeth. Near the base there is a connective apparatus consisting of a row of three alternating suckers and tubercles {c.app., fig. 65) ; two or three small suckers arc scattered down the stem. The buccal membrane has seven lobes, with corresponding ridges extending on to the arms, as shown in figure 63. The delicate little pen is lanceolate (fig. 71). The colour of this specimen in spirit is pale yellowish-brown, covered with dark purplish-brown chromatophores, on the mantle, iipper surface of the fins, head, buccal membrane, and arms (especially on their iianer surface). As seen in the figiu'e, a large niimber of U-shaped pigmented organs, most probably phosphorescent (see Joubin, 3 & 4 a), are scattered in irregular transverse rows on the lower sm-face of the mantle, head, and arms ; a few extend over to the upper surface, and one row surrounds each eye (fig. 64). The first three pairs of arms have one row each extending to their tips, whilst the larger ventral arms have three rows proximally, reduced to two distally. The exact systematic position of this little Cephalopod is not very easy to determine. I have placed it provisionally in the genus Histiopsis of Hoyle, from whose specimen it differs in the absence of a distinct web at the base of the arms, in the horny rings of the suckers, in the buccal membrane, in the contimiation of the fins beyond the mantle- apex, in the possession of one row only of pigmented organs on the first three pairs arms, and perhaps in the presence of the ' funnel-organ ' (Verrill's organ). The horny rings of the tentaciilar suckers arc very like those oillistioteuthis, to which genus it is no doubt closely related. Calliteuthis eeveesa, Verrill. One specimen of this widely distribvited species was caught in the Andaman Sea at a depth of 265 fathoms. CEPHALOPODA FROM THE CALCUTTA MUSEUM. 17 Taonius abtssicola, n. sp. (PI. 5. figs. 72, 73, 71^, 75, 76, 77, 78, 79, & 80.) Two sj)ecimens from the Laccadive Sea belong to this genus. The first, the large specimen shown in figure 72, comes from a depth of 902 fathoms. It is somewhat injiu*ed ; the skin has been rubbed off the mantle, fins, and head, and the eyes have burst out of their lids. The second specimen, from a depth of 1370 fathoms, is very much smaller and in a less satisfactory state of preservation. The principal measurements of the large specimen are as follows : — Length of mantle (lowei- surface) 7*6 centim. Breadth „ near edge 3-8 „ Length of fin-attachment 2*4 „ Breadth across combined fins l-~ ^^ „ of head between eyes '7 „ „ across eyes 2'8 „ Length of dorsal arm 2'5 ,, „ dorso-lateral arm 2'8 ,, „ ventro-lateral „ 3"3 „ „ ventral „ 2-8 „ „ tentacular „ 4'2 ,, „ >, club 1-1 ,, The mantle is loose, enclosing an ample cavity ; it diminishes gradually to the origin of the fin, and then suddenly to the narrow apex. The outline of the fins is egg-shaped. The mantle is attached by a lozenge-shaped cartilaginous plate to the back of the neck, and on both sides to the base of the siphon. The aperture of the funnel is covered by the sharply recurved upper lip (fig. 72), All previous observers have described the funnel of this species as destitute of valve.* On slitting up the funnel of this specimen and turning aside the two sides as shown in figui-e 7i, I found that the inner and upper wall is sharply bent inwards near the opening so as to form a deep pit w^here the sij)hon is fused to the head. On either side of this pit are the two cushions [c) noticed by Verrill (9), which in their normal position almost close u.p the lumen of the funnel. When these two cushions are pushed aside, a well-developed valve is disclosed rising from the bottom of the pit (fig. 74 v.). Behind the cushions, further down the funnel, are two triangular flaps, flattened and fastened by their base to the sides of the funnel {t.Jl., fig. 7i) ; they appear to be of a glandular nature, and probably correspond to the lateral pads described in other forms by AVeiss (10). On the inner and upper wall of the siphon is a wide A-shaped plate — the funnel-organ — very similar in shape to that figured by Weiss in Verania sicula. In the present instance it was so loosely attaclied that it readily came off; it is represented in flgtire 75, and its position is indicated by a dotted line in figure 74i. On the inner surface this plate is produced on either side into a triangular cap {i.e.), which fits closely as a glove * Since this was written M. Joubin (4) has described a small valve in the siphon of a new species of Taonius from the Atlantic. SECOND SERIES. — ZOOLOGY, VOL. VII. 3 IS -MR. E. S. GOODEICH ON A COLLECTION OF on to the flaps already described lying opposite them.* I have confirmed these observations on the second specimen. Contrary to Verrill's observations in two other species (9), I find on either side between the eye and the funnel a truncated olfactory papilla (fig. 76). It is slightly expanded and flattened distally, the flat oblique surface being concave. The head appears to have been narrow. The two eyes are very large and protrude from their sockets. The arms are thick, and of considerable length for this genus. The three dorsal pairs are provided on both sides with a well-developed lateral membrane (largest in the third pair), springing from the inner edge and supported by muscular thickenings arising from the base of each sucker (fig. 73). The ventral arms are also provided with such a membrane on the lower edge ; but it is rudimentary on the upper side, where on the contrary the outer edge of the arm is produced into a lateral keel. On all the arms we find two rows of suckers, largest on the third pair. The suckers (figs. 77, 78), very obliquely set on a short stalk, have a wide opening provided with a horny ring, armed on the distal margin only with about 14 squarish teeth. The papillary area is narrow. The tentacular arms are thick- stemmed, the clubs only slightly enlarged and bearing a lateral membrane on either side similar to that of the arms. The suckers of the club are compressed and considerably injured in this specimen ; they appear to be set in four rows, and of a peculiar conical shape (fig. 80). The stalk of the sucker sw^ells gradually to the base of the cup, where there is a thickened ridge ; it then narrows and expands again into a bell-shaped cwp, with an oblique opening. The margin of the horny ring is armed with eight or nine strong curved teeth, extending round the distal two-thirds of the circumference. The striated outer margin is frayed out into a fringe, but this is probably artificial. From the club extending down the stem are small short- stalked round suckers, the horny margin of which is armed all rovmd with blunt teeth (fig. 79). Distally at the base of the club these suckers are placed in four rows, which dwindle gradually to two rows proximally, where the suckers are very small and set in pairs on either side of a median groove. The buccal membrane has seven ridges ; the lobes are indistinctly marked. Purplish-brown chromatophores colour the fragments of skin adhering to the head and arms, the lateral membranes between the ridges, and the buccal membrane. The pen can be seen, wdthout dissection, as a narrow ridge starting from the nuchal ]ilate and exjianding posteriorly into a thin plate, narrowing again to form a slender cone, as figured by Pfefi'er for Taonius {Ilegalocranchia) maximns (6). The second specimen is very much smaller, and is possibly a young individual of the same species ; it is, however, not in a sufficiently good state of preservation to allow one to make certain of its specific identity. * In their normal position the jioints of the flaps are directed away from the middle line ; in figure 74 they iirc directed inwards owing to the stretching open of the funnel. CEPHALOPODA FEOM THE CALCUTTA MUSEU.AI. 19 OCTOPODA. Family PTEEOTI. ClKRHOTEUTHIS PACIFICA, Hoyle ? A small and mutilated specimen, captured at a depth of 265 fathoms iu the Audamau Sea, has been referred to this species. Family OCTOPODIDiE.* Octopus vuiiGABis, Lam. One large female from the Andamans, and one smaller male from Point Galle, Ceylon. These specimens resemble very closely our common Octopod, and I could find no important distinction between the European and Indian forms. Octopus granulatus, Lam. Eleven specimens have been placed in this species. Three come from Port Blair, three from the Andamans, one from Great Cocos Island, one from Bombay, two from the Southern portion of the Malacca Straits, and one from Maskat in Arabia. Octopus globosus, AppeUof. (PI. 5. fig. 81.) One specimen from the Nicobars, one from the Kabusa Islands (Mergui Archip.), five from the Southern jiortion of the Malacca Straits, three from Bombay, and one from Point Galle, Ceylon — in all eleven specimens have been referred to this species. The extremity of the hectocotylized arm of a male is shown in figure 81. Octopus pictus (Brock), ^SbV.fasciata, Hoyle. (PI. 5. fig. 82.) One male specimen from Port Jackson, Avhich agrees very closely with the specimen described by Hoyle in the 'Challenger' BejDort. The extremity of the hectocotylized arm, however, shown in fig. 82, difiers considerably from that described by Hoyle in Oct. maculosus (Proc. U. Phys. Soc. Edinb. vol. viii. 1883), w^hich he considers to be the same species. It seems probable that the var. fasciata may have to be separated as a distinct species. Octopus Januarii, Stp. Three specimens appear to belong to this widely distributed and abyssal species. One, a female, comes from a depth of 193 fathoms in the Bay of Bengal (lat. 20° 17' 80" N., long. 88° 30' E.) ; the othei- two are males captured at a depth of 271 fathoms in the Andaman Sea. The ridges on the hectocotylized tip of the arm in the male are more marked than in the figure given by Hoyle in the 'Challenger' Report (i), but in aU essential respects these specimens agree with his description. * I must express my thanks to Mr. W. E. Hoyle for kiudly cxaminiug some of these Octopods. 3* 20 ME. E. S. GOODEICH ON A COLLECTION OP Octopus macropus, Risso. With considerable doubt eight specimens have been referred to this species. Seven come from the Andaman Islands (three from Port Blair) and one from the Malacca Straits. Octopus aculeatus, d'Orb. Ten specimens from the Andaman Islands (six from Port Blair), one from Colombo, and one from Little Cocos Island. It is with some doubt that these have been placed in this species, wliich is not very thoroughly defined. Octopus levis, Hoyle ? One female specimen from Gopalpur, at a depth of 7 fathoms, has been provisionally placed in this species. It agrees closely, although not perfectly, with Hoyle's description. Octopus microphthalmus, n. sp. (PI. 5. figs. 83, 84.) One female specimen from Port Blair, Andaman Islands (fig. 83). This species is remarkable from the smooth cylindrical shape of the head and mantle, the eyes forming no prominence wliatever on the surface of the head. Tlie mantle ends obtiisely, and fits closely on to tlie head ; the mantle-opening, which is very narrow, reaches rather more than halfway from the siphon to the eye. The aperture of the eyelid is small. The funnel reaches to within 4 mm. of the edge of the web between the ventral arms ; it is attached to the lower su.rface of the head along almost its entire length. Tlie arms are rounded, and l)ear small somewhat conical suckers, which are arranged some distance apart. Although they are placed in two rows, the suckers are situated in zigzag fashion so as to approximate to the condition found in Eledone, for instance, where they are in one row. The mandibles are dark and strong (fig. 84, a Scb). The following are the princij)al measurements : — Length of mantle and head to lower edge of web between ventral arms . . 4'5 centim. ,, „ to mantle-edge 2"7 Breadth of mantle 2 „ head across eyes 1*5 Length of dorsal arm 8'6 , dorso-lateral arm 8'1 „ ventro-lateral ,, 6'9 „ ventral „ G'9 There is a small web at the base of the arms, reaching 1-6 cm. from the mouth between the dorsal arms, where it is longest (the inner surface of this web is the same between the bases of all the arms). The colour is yellowish -brown, inclining to dark brown on the upper surface of the mantle, head, and outer surface of the arms. CEPHALOPODA FEOM THE CALCUTTA MUSEUM. .21 TAst of Works referred to in the Text. 1. HoYLE, W. E. — Challenger Reports, vol. xvi., pt. 4i, "Report on the Cephalopoda/' 188G. 2. JouBiN, L. — " Cephalopodes d'Amboine." Revue de Zool. Suisse, vol. ii., 1894. 3. JouBiN, L. — " Quclques organes colores, etc." Mem. Soc. Zool. de France, vol. vi., 1893. 4. JouBiN, L. — "Resultats des Campagnes Scieutifiques de Prince de Monaco": fasc. ix., 1895. 4fi!. JouBiN, L. — "Note sur I'appareil photogene d'uu Cephalopode." C. R. Soc. Biol. vol. v., 1893. 5. D'Orbigny, a., et Ferussac. — Hist. Nat. des Cephalopodes acetabuliferes. Paris, 1835-48. 6. PfEFFER, G. — " Die Cephalopoden des Hamburger Nat. Mus." Abhandl. d. Naturw. Ver. Hamburg, Bd. 8, 1884. 7. Steenstrup, J. — " Hectocotyldannelsen, itc." K. Danske Vid. Selsk. Skriv., Rk. 5, Bd. 4, 1856. Transl., Ann. Mag. Nat. Hist. ser. 2, vol. xx., 1857. 8. Vkrany, J. B. — Cephalopodes de la Mediterranee. Giines, 1851. 9. Verrill, A. E.— "Ccphalopods of the N.E. Coast of America." Trans. Conn. Acad. vol. v., 1880* and vol. vi., 1884. lo. Weiss, E. — " On some Oigopsid Cuttle-fishes." Quart. Journ. Micr. Sci. vol. xxix., 1888. REFERENCE LETTERS. a. Arm. loc. Striated region of loculi. ap.f. Apical fin. lolf.f. Left olfactory fold. ap.prol. Apical prolongation of the mantle. m. jNIembrane. ap.s. Apical set of suckers. mo. Mouth. b.m. Buccal membrane. m.s. Modified sucker. b.t. Basal tooth. nit. Mantle. c.app. Connective apparatus. olf.p. Olfactory papilla. ch.m. Chitiuous margin. ph.org. Phosi)horescent organ. d.a. Dorsal arm. pp. Pigmented patch. e. Eye. r.s. Rudimentary sucker. e.l Eyelid. s. Sucker. /• Fin. si. Siphon. /•/• Lateral membrane developed into a fiap. so. Socket. h. Hook. t. Tentacular arm. hd. Head. t.c. Triangular cap. i.e. Inner cone. t.jl. Triangular flap. i. 1.171. Inner lateral membrane. V. Valves. k. Keel. v.a. Ventral (4th) arm. I.m. Lateral membrane. v.h.a. Ventral hectocotvlized arm 22 ME. E. S. GOODEICH ON A COLLECTION OF EXPLANATION OF THE PLATES. Plate 1. Inioteuthis maculosa, n. sp. Fig. 1. View of lower surface, nat. size. 2. Enlarged view of the horny ring of a tentacular sucker. 3. Enlarged side view of a tentacular sucker. Sepia singalensis, n. sp. Fig. 4. Outline of the mantle and fins, and figure of the pen (inner surface), nat. size. 5. Enlarged view of a spermatophore. 6. Upper {b) and lower (a) mandibles, nat. size. 7. Enlarged view of a portion of the horny ring of a small tentacular sucker. 8. Horny ring of a small sucker of an arm. Sepioteuthis indica, n. sp. Fig. 9. Outline of the mantle and fins, reduced. 10. Figure of the pen of another specimen, reduced. IL Enlarged view of a portion of the horny ring of an apical sucker of the tentacular club. 12. Enlarged view of the apex of the tentacular club. 13. Side view of the head, showing the olfactory fold, nat. size. 14. Upper (6) and lower (a) mandibles, nat. size. 15. Horny ring of a sucker of the buccal membrane, enlarged. 16. Portion of the left 4th arm of a male, enlarged. 17. Edge of the horny ring of a sucker of the 3rd arm, enlarged. 18. Large tentacular sucker, x 4 diam. 19. Portion of the edge of the horny ring of tentacular sucker, enlarged. Plate 2. Loligo indica, Pfeffer. Fig. 20. Edge of the horny ring of an arm-sucker of a male, enlarged. 21. Horny ring of a sucker of the buccal membrane, enlarged. 22. Lower view of the left 4th arm of a male, showing the hectocotylization, nat. size. 23. Portion of the hectocotylized region of the same, inner view enlarged. 24. Horny ring of a small tentacular sucker, enlarged. 25. Enlarged view of a portion of the horny ring of an apical sucker of the tentacular club. 26. Horny edge of an arm-sucker of a female, enlarged. 27. Enlarged view of a portion of a large tentacular sucker of the same. 28. Enlarged view of a spermatophore. CEPHALOPODA FROM THE CALCUTTA MUSEUM, 23 Loliolus Investigatoris, u. sp. Fig. 29. Upper view of a male, uat. size. 30. Outline lower view of the mantle and fins, nat. size. 31. Upper view of the pen, nat. size. 32. Lower view of the hectocotylized 4th left arm, uat. size. 33. Enlarged inner view of a portion of the same. 34. Enlarged views of the upper [b) and lower [a) mandibles. 35. Horny ring of a tentacular sucker, enlarged. 36. Side-view of an arm-sucker, enlarged. 37. Edge of the horny ring of the same, enlarged. Abralia andainanica, n. sp. Fig. 38. Lower view, nat. size. 39. Outline upper view of mantle and fins, nat. size. 40. Enlarged view of the tentacular club. 41. Upper («) and side (6) views of the pen of a smaller specimeUj nat. size. 42 & 43. Front and side views of an arm-sucker, enlarged. 44&45. Front and side views of a tentacular suckei', enlarged. Plate 3. Abralia lineata, n. sp. Fig. 46. Upper view, nat. size. 47. Lower view, enlarged. 48. Enlarged view of the tentacular club. 49. Horny ring of an arm-sucker, enlarged. 50. Horny ring of a tentacular sucker, enlarged. Cheiroteuthis macrosoma, n. sp. Fig. 51. Lower view, nat. size. 52. LTpper («) and side (6) views of pen, nat. size. 53. Diagram of a section of pen across anterior region (6) and cone («), enlarged. 54. Upper (6) and lower [a] mandibles, nat. size. 55. Sucker of the ventral arm, enlarged. 56. Socket («) at the base of the siphon, and cushion on the mantle {b), uat. size. 57. Teeth of the radula, enlarged. Plate 4. Cheiroteuthis pellucida , n. sp. Fig. 58. Lower view, nat. size. 59. Socket at the base of the siphon, enlarged. 60. Sucker of the arm, enlarged. 61. Tentacular sucker, enlarged. 24 ■ ON CEPHALOPODA FEOM THE CALCUTTA MUSEUM. Histiopsis Hoylei, n. sp. Fig. 62. Lower view, nat. size. 63. Enlarged view o£ the mouth, buccal membrane, and the base of the arms. 64. Enlarged view of the right side o£ the head. 65. Enlarged view of the tentacular club. 66. Upper view in outline of the mantle and fins, nat. size. 67. Enlarged side view of a large tentacular sucker. 68. Enlarged left-side view of the funnel and mantle-edge. 69 & 70. Enlarged side and front views of an arm-sucker. 71. Upper view of the pen, nat. size. Plate 5. Taonius abyssicola, n. sp. Fig. 72. Lower view, nat. size. 73. Inner view of a portion of the dorsal arm, enlarged. 74. Enlarged view of the base of the head and siphon and mantle slit up along the median line and turned aside. 75. Funnel-organ, lower view, removed from its place on the wall of the siphon, indicated by a dotted line in fig. 74, enlarged. 76. Enlarged view of the olfactory papilla. 77. Side view of an arm-sucker, enlarged. 78. Horny ring of the same, enlarged. 79. Enlarged view of a portion of the horny ring of a small sucker at the base of the tentacular club. 80. Front (a) and side (6) views of a tentacular sucker. Octopus globosus, Appellof. Fig. 81. Enlarged view of the extremity of the hectocotylized arm. Octopm pictus (Brock), vax.fasciatus, Hoyle. Fig. 82. Enlarged view of the extremity of the hectocotylized arm. Octopus microphthalmus, n. sp. Fig. 83. Lower view, nat. size. 84. Lower (a) and upper (6) mandibles, enlarged. I Goodricl'i Tr,ajnis Linn . Soc. Zool . Ser,2 Yol . VII Pl 1 .^ 1 -. - ■«a |l " ''■■*.,^-.--' ^■| />'''^. 5 ,^-^'-.-^'?3??V 0.9 30 U i 28 36 Jr»,? 66 . 'C7 E.SGoodricK del . ATl.Hamraonol lith . "^ af-p, rol. ph.Oiu. 47 CEPHALOPODA FROM CALCUTTA MUSEUM Hanhart iinp Gflodru'l! Iran,; : -'ht ;..i''oiw/! ' ■ '" -■ - ;> f. \. i#^^^ ^. -^^:-^ 1?^ ' ' ^ K 1 ^r \ X y -J- / '•■-■e'/ tes^, / I fi ,§ ,# f^ 4p^' /'% %1 r GEPHALOPOSA FROIJ ;,V,"l,0U7TA MUSEUlvr Tp^-^WS LlI'.'N 8oO.ZoOT,.o'KR 2\0I.^ll Pl 74- \ 't /i # ¥ •'^^ y ^v 4 ^ fe.: \^y (-1 rm S^i.,. 'Yl / A.H.Hanin\onrl_ liti-i , iianhd-pi liii}. CE PH AL P On/^. F ROM CA POUT T A T,4U ST. UTs I LINNEAN SOCIETY OF LONDON. MEMORANDA CONCEKNING THANSACTIONS. The First Series of the Transactions, containing both Botanical and Zoological contributions, has been completed in 30 Vols., and a few entire sets are still for sale. Only certain single volumes, or parts to complete sets, may be obtained at the original prices. The price of the Index to Vols. l-2.'5 is 8s. to the public, and 6s. to Fellows; to Vols. 26-30, 4s. to the public, and '3s. to Fellows. The Second Series of the Transactions is divided into Zoological and Botanical sections. The prices of the Zoological parts of these which have been published are as undermentioned (for tlie Botanical parts see Botanical wrapper) : — When Price to the Voli.n.e. Published. Public. £ s. d. Second Series. — Zoology. I. Part I. 1875 1 4 . Part II. 1875 6 . Part III. 1876 1 8 . Part IV. 1877 16 . Part V. 1877 18 . Part VI. 1877 1 2 . Part VII. 1878 110 . Part VIII. lS7t) 1 . II. Part I. 1870 1 4 . Part II. 1881 15 . Part III. 1882 1 8 . Part IV. 1882 7 6 . Part V. 1882 3 . Part VI. 18S3 1 . Part VII. 1883 5 . Part VIII. 1883 3 . Part IX. 1883 3 . Part X. 1884 4 G . Part XI. 1«84 10 . Part XII. 1885 6 . Part XIII. 1884 6 . Part XIV. 1885 6 . Part XV. 1885 4 6 . Part XVI. 1885 5 . Part XVII. 1886 3 . Part XVIII. 1888 2 6 . III. Part I. 1884 1 14 . Price to Fellowa. £ s. d. 18 4 6 ] 1 12 13 6 16 6 1 7 15 18 11 6 1 1 5 6 2 3 15 3 9 2 3 2 3 3 6 7 6 4 6 4 6 4 6 3 6 3 9 2 3 2 16 6 When Price to the volnnie. t> 1 1- i i t» ui- Publislied. Public. £ s. d. Second Series. — Zoologt {(onllnucd). III. Part II. 1884 112 . . . . Part III. 1885 1 10 Part IV. 1885 8 . . . . Part V. 1887 8 Part YI. 1888 6 IV. Part I. 18SC 1 4 . . . . Part II. 1887 I 8 Part III. 1888 16 . . . . V. Part I. 1888 12 . . . . Part II. 1888 5 Part III. 1889 1 7 . . . . Part IV. 1890 12 .... Part V. 1890 6 Part VI. 1891 12 .. .. Part VII. 1891 6 .... Part VIII. 1892 8 . . . . Part IX. 1892 12 . . . . Part X. 1893 1 8 . . . . Part XI. 1894 2 6 . , . . VI. Part I. 1894 2 .... Part II. 1894 1 11 .. .. Part III. 1894 10 Part IV. 1896 1 4 .... Part V. 1896 10 . . . . Part VI. 1896 8 . . . . Part VII. 1896. . . . 12 . . . . VII. Part I. 1896 (I 10 (.1 Price to Fellows. 1 4 1 2 6 6 6 4 6 18 1 1 12 9 3 9 1 9 4 6 9 4 6 6 9 1 1 2 1 10 1 3 3 7 6 18 7 6 6 9 / 6 2nd Ser. ZOOLOGY.] [VOL. VII. PART 2. THE (c^f/l. ri^ IRANSACTIONS 16i/7 OF THE LINNEAN SOCIETY OF LONDON, AMPHIPODA FE(.)M THE COPENHAGEN MUSEUM AND OTHER SOURCES BY The Rev. THOMAS R. R. STEERING, M.A., F.R.S., F.L.S. LONDON PRINTED FOR THE LINNEAN SOCIETY BY TAYLOR AND FRANCIS, RED LION COURT. FLEET STREET. SOLD AT THE SOCIETY'S APARTMENTS, BURLINGTON-HOUSE, PICCADILLY, W., AND BY LONGMANS. GREEN, AND CO., PATERNOSTER-ROW. May 1897. [ 25 II. Amphipoda from the Copenhagen Mmeiuii and other Sources. By the Rev. Thomas R. R. Stebbing, M.A., F.H.S., F.L.S (Plates 6-14.) Head 19th November, 1896. Introductom Remarks. The Zoological Museum at Copenhagen is rich in Amphipoda. It is rich also in living authorities on this group of Crustaceans, since Inspektor Dr. Meinert and Professor Liitken are two of its Directors, and Dr. H. J. Hansen is on the staff. This might well seem a happy concurrence of a fine collection in the hands of those well qualified to make its value known to the world. But the masters in science find their work continually expanding, while time remains remorselessly inelastic. Hence it is that these gentlemen, being themselves beset by other duties, have passed over to me the task of reporting on the Amphipoda of the Danish University. In this first memoir on the subject some of the more striking rarities are described, together with one or two of a less uncommon type. As the collection is not local but cosmopolitan, the opportunity has been taken of bringing mto notice certain other new or insufficiently known forms, in addition to those received from Denmark. For some of these I am indebted to Professor W. A. Ilaswell, D.Sc, of Sydney, New South Wales, and G. M. Thomson, Esq., E.L.S., of Dunedin, New Zealand. A specimen, which in the Report on the ' Challenger ' Amphipoda was unavoidably presented without adequate ceremony, and which in conseqiience subsequently became the subject of misunderstanding, is now set forth with due illustration, and a specimen from the Clyde, some years ago described without figures, now in like manner makes a more formal appeal for acceptance as the representative of a valid species. The range of the various specimens described extends from the shore to the deep sea, from Cuba to Ceylon, from the North Atlantic to the South Pacific, from the western coast of Scotland to the eastern coasts of Australia and New Zealand. Nine genera and ten species are discussed. Six of each are new. The species afford an illustration of two difficulties which not unfrequently arise in systematic natural history. Some of them are so like their jireviously known neighbours that a short-sighted jierson might think them not worth distinguishing. Others stand oddly apart, with so queer a combi- nation of characters that more than one existing family must look at them askance, imwilling to embrace, reluctant to repulse, in truth not very well able either " to do with them or without them." Opinions will differ on the policy of promptly establishing new families for eccentric forms, or of postponing that responsibility to as late a date as SECOND SERIES. — ZOOLOGY, VOL. VII. i 26 EEV. T. E. E. STEBBING ON AMPHIPODA FEOM possible. In the amiable endeavour to oblige the partisans of either view, I offer tentatively a new family for one of these perplexing species, boldly assign one to an old family, and leave one for the present homeless. Fam. ORCHESTIID^. Parhtale, n. g. First cmtennce longer than the peduncle of the second. First maxillm with the palp one-jointed, not extending beyond the distal margin of the outer plate. Max'illipeds with the palp four-jointed. Both pairs of gnathopods subchelate, differing in the two sexes. The third uropods carrying a minute inner ramus. Telson bipartite. The character of the Orchestiidse has to be slightly modified for the reception of this genus, since in it the third uropods are not absolutely one-branched, but show a sradation towards the more normal biramous condition. Parhyale fascigek, n. sp. (Plate 6.) Specimens in spirit are slightly iridescent. The skin has some minute setules scattered over it. The second and third pleon-segments arc squared at the postero- lateral angles. The fourth segment almost reaches to the telson, overlapping the very short fifth segment, whUe the sixth is dorsally obsolete. The telson is divided to the base, its two oblong or sometimes somewhat triangular leaves standing nearly upright. Eyes oval, dark, obliquely set near the top and fi'ont of the liead ; ocelli numerous. First antennce. The second and third joints together approximately equal in length to the much stouter first joint ; the flagellum of ten or eleven joints is longer than the peduncle. Second antennce. The last two joints of tlie peduncle nearly equal in length ; the flagellum not once and a half as long as the peduncle, with about twenty joints in the male and fourteen to sixteen in the feniale. Upper lip. The apical margin is rounded and furred in the usual manner. Mandibles. The cvitting-edge has six teeth. The secondary plate on the left mandible is strong and quinquedentate, on the right it is slighter, with coml>like, slightly concave edge ; the spine-row on the left attains the number of six spines, which have the appearance of plumose sette ; the molar tubercle is strong, prominent, finely denti- culate, with a hairy tuft at one corner, and a long feathered seta at the other. Above it and a little in advance is the articulating process. Lower Up. The lateral processes are short. First maxillce. The inner plate is slender, surmounted by two feathered setse, of Avhich the inner is the shorter. The outer plate is rather liroad, surmounted by nine spines THE COPENHAGEN MUSEUM AND OTHEE SOUECES. 27 variously denticulate, in two rows, which are set so closely together that it is difficult to count and discriminate the spines. The palp is slender, tipped with a minute hair and small seta. There is often a slight constriction of the margins near the apex, as though a second joint were being thought of. Second maxillcc. The setae round the apex of the outer plate are longer than those of the inner. The fringe on the inner plate is bounded by a seta conspicuously longer than the rest. MaxilUpeds. The inner plates have the usual setse and three apical teeth. The outer plates reach but little beyond the first joint of the palp, and have their spinules set a little Avithin the margin. Both the second and third joints of the palp are broadly lobed at the inner distal extremity. The third joint has a little rounded and shining process for the aj^ex of its outer margin. On the inner surface there is a graduated row of spines, and in the male a dense tuft of setae on the outer surface, from among which the sharjD curved finger projects. The inner margin of the finger carries some spinules or small hairs. First (jnuthopods. The side-plates are widened below, and have the front margin straighter than the hinder one. The fifth joint is distally widened, and has the projecting hind margin fringed with setae. The hand or sixth joint is as long as the preceding, and in the male fully as wide, but narrower in the female. The hind margin has a central fringe of setix', bounded by a slight contraction in the width of the hand. The palm is rather oblique, fringed with little hairs and setules, and carrying two unequal but stoutish spines at the extremity, against which the rather broad finger impinges. There are spines on the inner surface of botli hand and wrist, and minute hairs on the inner margin of the finger. Second gnathopods. The side-plates are oblong, with rounded corners below, but with the hind margin somewhat excavate above. The branchial vesicles of these limbs and the four following pairs have at the base a small vesicle accompanying the ordinary large one. The marsupial plates of the female are long, distally acute, and, at least in the distal part, closely fringed. As in the first pair, the second joint widens distally, the third is short, the fourth is of nearly uniform breadtli, Imt having the hind margin longer than the front. The wrist in the male is almost triangular, with convex front border, and behind masked by the fourth joint, whereas in the female it protrudes a spine- fringed lobe between that joint and the hand. In the male the band is massive, with very oblique palm, uniformly convex till near the distal end, bordered Avith nuniei'ous little spines, over Avliich the long and broad finger closes tightly, sending its point into a little pocket on the inner surface of the hand, from which arises a small group of stoutish spines. The hind margin is almost smooth, but has a small indent similar to that in the first pair. In the female the hand is less massive, but still much larger than the Avrist, Avith a very oblique palm, leaving a shorter hind margin, Avhich is fringed with spines. In both sexes the finger has little hairs set at right angles to the inner margin. First peraopods. The side-plates are a little broader than the preceding pair, but similarly shaped. The fourth joint is longer and much broader than the fifth or sixth. 4* 28 EEV. T. R. E. STEBBING ON AMPHIPODA FEOM The finger is short, curved, with a spinule from its inner margin cnrviug towards the small but decided nail. The fingers are similarly shaped in all the perteopods. Second perc^opods. The side-plates are broader than the preceding pairs, with the hind margin doubly excavate above. The limbs closely resemble the preceding pair. Third perceopods. The side-plates are broad, bilobed, not very deep. The second joint has the breadth and depth about equal, with the margins very slightly indented. The fourth joint is much broader, but not longer than the sixth, which is narrower but a little longer than the fifth. The fourth joint has spines on both margins, the apical groups l)eing large. The same applies to the fifth joint, except that its hind margin is only armed at the apex. The sixth joint has spines along the front. Fourth perceopods. These are similar to the preceding, but with the joints from the second to the sixth decidedly larger. Fifth 2JercBopods. Tlie side-plates are not bilobed. The limbs are like the jireceding pair, but larger. Fleopods. There are two, or in some cases three, small coupling-spines. The spines of the inner margin of the first joint of the inner ramus have a distal thickening, but no cleft could be distinguished. The rami appear to be as nearly as possible eqvial in length, with about thirteen joints apiece, each carrying the usual pair of plumose setae. TJropods. The first pair are the longest, with peduncle longer than the rami, having spines on its iipper margin and a large spine at the apex. The rami are of equal length, with one large and other small spines at the apex, the inner having two in addition on the upper margin. The second pair are much shorter, but similarly armed. The third pair are short, the peduncle not being so long as the telson. It carries some apical spines. So does the outer ramus, Avhich is a little shorter. The inner ramus is conical, almost rudimentary, tipped with a minute seta. Lenyth. In the partially-folded position which seems natural to animals of this genus, the length of the specimens averages a quarter of an inch. ILah. Harbour, Antigua, West Indies (specimens received from W. E. Forrest, Esq.). Specimens from the Copenhagen Museum were labelled " St. Thomas, Havnen, 1877. Eggersr The specific name refers to the appearance presented by the extremity of the maxil- lipeds, whicli in the male is very striking. Fam. LYSIANASSID^. Lysianax cinghalensis, n. sp. (Plate 7 A.) First three segments of plcon large, postero-lateral angles of third segment rounded. The etjes large and black, occupying most of the svu-face of the head, on the top of which they meet. First antennce. First joint tumid, scarcely longer than deep, nearly twice as long as the second and third combined ; flagellum six-jointed, shorter than first joint of peduncle ; accessory flagellum three-jointed, less than half the length of the primary. THE COPES^HAGEN MUSEUM AND OTHEK SOUECES. 29 Second antennm. In the male about two-thirds the length of the animal, the ultimate joint of the peduncle considerably longer than the penultimate, flagellum of about thirty- five slender joints. Mouth-organs closely agreeing with the generic account given by Sars in ' The Crustacea of Norway.' The slender mandibular palp has the first joint characteristically elongate, and there are but few spines on the paljj of the first maxillae. First gnathopods. The side-plates widened below, so that they are as wide as deep ; the second joint as long as the four succeeding joints combined, the third larger than the fourth, the fifth much wider but rather shorter than tlie narrow, taj)ering sixth ; the finger curved, small. Second gnathopods. The second and third joints slender and elongate, the fifth as long as the third, the sixth more than half the length of the fifth, gradually widening distally, with short transverse palm, on which the finger closes tightly, without overlapping it. First and second permopods. The side-plates of the second pair are deeply and rather widely excavate behind. The second joint of the limbs comparatively short ; the fourth, fifth, and sixth joints rather long, with some plumose setae. Third percBopods. The side-plates wider than deep, pretty evenly bilobed ; the second joint as broad as long, smaller than the side-plates ; the fourth joint rather broad, produced to an acute point. Fourth and fifth perceopods. The second joint broader and much longer than in the preceding paii", roundly produced behind. Branchial vesicles strongly pleated. TJropjods slender. First pair with the rami subequal, more than three-fourths as long as the peduncle, each with three marginal spines. Second pair, with subequal rami, almost as long as the pedimcle ; the outer ramus with four marginal spines, the inner constricted near the end, with a spine in the notch. Third pair with the peduncle longer than the rami, produced to a point at the outer angle ; the inner ramus a little shorter than the outer, both with long setae on the inner margin. Telson oval, not reaching far along the peduncle of the third uropods, having a feathered setule on each lateral margin, and the apex smootlily rounded. Length three-tenths of an inch. Labelled " Trincomali (Ceylon), 3/89, surface. K. Fristedt," Copenhagen Museum. Lysianax cubensis, u. sp. (Plate 7 B.) Lateral angles of the head considerably produced, broadly rounded. Postero-lateral angles of third pleon-segment quadrately rounded. FJi/es reniform, moderately large. First antenncB. First joint large, longer than deep, not very much longer than second and third combined, neither of tliese being extremely short; flagellum six-jointed, shorter than the peduncle ; accessory flagellum three-jointed, less than half the length of the primary. Second avtennce. Last two joints of the peduncle (in the female) subequal ; flagellum broken. 30 EEV. T. R. R. STEBBING ON AMPHIPODA FROM Mouth-organs of the character usual in the genus, but palp of first maxilla with the apex rather Avide, carrying one little spine and six very distinct teeth. First QRcdhopods. Side-plates widened below, deeper than Avide. The second joint shorter than the four succeeding joints combined, the fifth rather stouter than the tapering sixth and quite as long ; finger small. Second gnathopods. The second and third joints rather long and slender, the fifth as long as the third, the sixth much more than half as long as the fifth, at first gradually but distally rather abruptly widened ; palm transverse, finger very small. First and second prrtropods. Side-plates of the second pair broad, the excavation being moderate in breadth and deptli. The joints of the limbs of moderate dimensions, fringed with smooth setse or spines. Third perccopods. Side-j^lates much wider than deep, the front lobe deeper than the hinder. Second joint much wider than deep, almost as large as the side-plate, the fourth joint little widened. Fourth per mopods. Second joint longer than broad, front margin strongly bowed, hind margin sinuous, fourtli joint scarcely widened. Fifth perceopods. Second joint much larger than in the preceding pairs, very broad, but rather longer than broad ; fourth joint scarcely widened. Marsupial plates slender, branchial vesicles rather strongly pleated. TJropods. First pair Avith the rami subequal, slender, carrying a few margmal spines, somewhat shorter than the peduncle. Second pair shoi-ter than the first ; peduncle scarcely as long as outer ramus, which lias four marginal spines ; inner ramiis slightly shorter, stout, with two spines, then strongly constricted with a spine in the notch. Third pair much shorter than second ; peduncle rather longer than the rami, with one lateral margin running out into a point, the other notched near the middle, the rami almost smooth, eqiial. Tel son reaching little beyond the sides of the sixth pleon segment, little longer than broad, boat-shaped, apex truncate. Colour of specimen, in spirit, brownish. Length about three-tenths of an inch. Specimen labelled " Zi/sianasscc aff". Paa en Reise til Cuba." Copenhagen Museum, Studer Collection. Fam. STEGOCEPHALIDiE. AXDANIOTES, n. g. Head wdth small rostrum. First segment of peragon the longest. Sixth segment of pleon longer than the fourth or fifth. Each of the first three side-plates socketed in a groove on the underside of that next succeeding ; the fourth very large, subequal in breadth and depth, with a wide shallow excavation behind, overlapping the fifth and in part the sixth. Eyes wanting. First antennse with very thick first joint ; flagellum tfipering, the first joint A'cry long, longer than the remaining three combined ; the accessory flagellum small, one-jointed, tipped Avith a long spine. Second antennae with the last joint of the peduncle shorter than the penultimate, flagellum short. Epistoma carinate. U2:)per THE COPENHAGEN MUSEUM AND OTHER SOUECES. 31 lip broader tlian deep, slightly bilobed. Lower lij) with the front lobes wide apart, not larger than the hind lobes, and snrmonnted with a single spinule at the outer corner. Mandililes a slightly sinnous oblong in shape, with straight smooth cutting-edge ; a tooth-like accessory plate on tbe left * mandible. First maxilla? with inner plate rather large, bordered with 7-11 long plumose setae ; outer plate moderately broad, carrying nine slender spines and a tuft of setules ; the palp one-jointed, nearly reaching the end of the outer plate, tipped with seven setae or slender spines. Second maxillae with inner plate very broad, with a fringe of 18 or 19 setae, most of them plumose ; the outer jilate shorter and greatly narrower, tipped with nine setae. Maxillipeds with inner plates very broad, the apical margin sloping outward, with three little spine-teeth; the outer plates not nearly reaching the end of the palp's second joint, fringed with 13 spine-teeth on the inner margin ; the joints of the palp successively diminishing in size, the third and fourth slender and small. Appendages of the perteon nearly as in Andania. Uropods with the peduncles robust, much longer than the rami; both peduncles and rami successively diminishing. In the male, outer ranuis of first pair thick, curved, smooth, inner rather shorter, straight, slender, each with two marginal spinules ; rami of second pair slender, smooth, subequal ; rami of third pair minute, the outer nearly twice as long as the inner, with a tiny second joint. In the female all the rami slender ; those of the third pair- not minute, subequal, nearly as long as the peduncles. Telson broadly oval, but ending almost acutely, cleft nearly to the middle, but without any dehiscence, shorter than the peduncles of the tliird uropods. Andaniotes corptjlentus (Thomson). (Plate 8.) 1882. Anonyx corpulentus G. M. Thomson, Trans. New Zealand Institute, vol. xiv. p. 231, pi. 17. figs. 1 a-f. 1888. Andania abijssorum Stabbing ' Challenger ' Amphipoda, p. 739, pi. 37. 1893. Stegocephalus abyssorum Delia Valle, Gammaiini, p. 629, pi. 59. fig. 38. Head vdth lateral angles rounded and below them produced downward in long straight triangular lobes hidden under the first side-plates, below which the mouth-organs of the down-bent head are visible. Third pleon-segment with the postero-lateral angles narrowly rounded, the dorsal line distally bent abruptly downward, having (in the male) two little eminences below the bend, the distal margin somewhat squared ; the fourth segment dorsally convex ; the fifth depressed ; the sixth long, dorsally convex, forming two longitudinal eminences, between which the telson is concealed in a lateral view. First antenncp. The third joint of the pedimcle is transversely oval ; the first joint of the flagellum carries transparent filaments ; the setiform spine at the apex of the accessory flagellum is longer than the joint. Second antenme. The flagellum is eight-jointed. First (inathopods. The side-plates are roughly triangular. The second joint is long and broad, stronger in the male than in the female ; the third joint longer than broad ; the fifth joint in the male longer and much wider, in the female wider but only little * Not on the right, as stated in tlie ' Challenger " Arnphipoda, p. 739. 32 REV. T. R. E. STEBBING ON AMPHIPODA FROM longer thau the sixth, with many setse on both margins, those in front elongate ; the sixth joint abruptly narrows distally, so as to leave no palm, carrying long setse in front, more in the male than in the female, and a row of shorter ones at right angles to the hind margin ; the finger is small, curved. Second gnatlioimds. The second joint is slender, curved at the base, the third longer than the fourth, the fifth and sixth rather slender, subequal ; the curved finger impinging against the sinuous hind margin of the sixth joint, which is armed with plumose setae. Third jyerceopods. The second joint is scarcely dihxted ; the fourth is not very wide, acutely outdrawn below. Fourth i^erceopods. Second joint twice as broad as in the preceding pair, fourth joint also larger. Fifth perceopods. Second joint longer and much broader than in the preceding pair, subequal in length to the rest of the limb, broadly overlapping the third joint ; the fourth joint rather wide, but much shorter than in the preceding pairs. Pleopods. Coupling-spines rather long. Length nearly three-tenths of an inch. Hub. New Zealand. A male and a female specimen received from G. M. Thomson, Esq., F.L.S., the first describer of the species. A female specimen was also taken by the ' Challenger ' Expedition. Earn. PHOXOCEPHALID^. PONTHARPINIA, n. g. 1880. Urothoe Haswell, Proc. Linn. Soo. N. S. Wales, vol. iv. p. .^^o. 1891. Harpinia? Stebbing, Trans. Zool. Soo. London, vol. xiii. pt. 1, p. l. Back very broad, tapering to the rostrum and telson. Third pleon-segment setose on the lower hind margin. Eyes small, lateral, set rather far back. Eirst antennae with first joint tumid, second more slender, setose, third short ; accessory flagellum many- jointed, more than half as long as the primary. Second antennae with the basal joints of the peduncle short and stout; the penultimate long, broad, and setose; the ultimate much shorter and nai'rower, but also carrying long setae ; the flagellum shorter than the peduncle. Upper lip distally rounded, wide. Lower lip quadrilobate. Mandililes with cutting-] )late and left mandible's accessory plate small, divided into a few teeth ; spine-row of 8-10 spines, the first on the right mandible conspicuously the largest (perhaps representing the accessory plate) ; molar small, prominent, tipped with a few imeqtml spinules ; palp much longer than the trunk of the mandible, third joint rather shorter than second, Avith many long setae near the base and the apex. Eirst maxillae : inner plate small, carrying three short setae, outer with eleven spines, very slight in size and armature; second joint of palp with 4 spinules and 4 setules on truncate apex. Second maxillse : inner j)late shorter and narrower than the outer, its armature not occujiying more than half the inner margin. Maxillipeds with the plates narrow and not very long ; the outer scarcely reaching the middle of the long and broad second joint of the palp, fringed with half a score of graduated spines ; the fourth THE COPENHAGEN MUSEUM AND OTHER SOUECES. 33 joint of the palp slender and curved, considerably longer than the third. Gnathopods apparently varying in the two sexes. First and second j)erajopods with the fourth joint much longer than the fifth or sixth ; fifth much wider than the sixth, fringed with long spines at the hinder apex ; the finger small, spine-like, scarcely so large as a knife-like spine on the apex of the sixth joint. Third and fourth peneopods with the second, fourth, and fifth joints greatly widened ; fifth pair much smaller than the others, its second joint much expanded, Avidest distally, produced to the end of the fifth joint ; third joint wider than those folloAving, which are all narrow and small ; the finger straight, acute. First uropods with a long spine at apex of peduncle, rami suhequal, rather longer than peduncle, spinose ; second pair short, rami equal, one sjjinose ; third pair with lanceolate rami. Telson divided into two suboval plates. Marsupial plates of the female narrow. The generic name is intended to indicate the intermediate character of this genus between such forms as those in the genera Urothoe and Hailstorms of the Pontoporeiidte and Harpinia in the Phoxoeephalidre. By the character of the mandibles it is better placed in the latter family. PoNTHARPiNiA PiNGUis (Haswell). (Plate 9B.) 1880. UrotJwe jnnffuis Haswell, Proc. Linii. Soc. N. S. Wales, vol. iv. p. 3.25, pi. 19. fig. 2. 1882. „ „ „ Catalogue of the Australian Stalk- and Sessile-eyed Crustacea, p. 240. 1891. Harpinia t jnngiiis Stebbing, Trans. Zool. Soc. London, vol. xiii. pt. 1, p. 4. 1893. Urolfioe irrostruta ? Delia Valle, Gammarini, p. 667. Head long, tapering from a broad base. First side-plates tending to quadrate, but widened below ; fourth with rounded lower margin, widest just below the shallow exca- vation ; fifth broad, not deep, the binder lobe the deeper ; seventh very small. Third pleon- segment with a very small produced point at the lower hinder angles, above which the hind margin is finely serrulate. The fourth segment ajjpears dorsally to overlap the fifth and sixth. First antennce. Fhigellum consisting of 15 joints, accessory flagellum of 10 ; in a female specimen of 9 and 7 respectively. A peculiarity of these joints is that the apical margin being oblique, they overlap one another. This is shown in Haswell's figure of the primary flagellum, though he does not mention it in his text. Second antennce. Last joint of peduncle narrow at base, thence a little widening ; flagellum in female with 10 joints, shaped as in the first pair. Haswell's figure shows 21 joints. Tipper lip wider than deep. Lower lip with very small principal lobes. The mouth-organs in general are small, except the palps of the mandibles and maxillipeds. Tirst gnathopods. 2 . Second joint reaching much beyond the side-plate ; fifth nearly as long as second and rather wider, fusiform; sixth shorter and rather narrower, widening from a narrow base, then preserving an almost iiniform width to the transverse slightly convex palm, wliich ends in a short tooth, tlie convex front margin of the widened part SECOND SEIIIES. — ZOOLOGT, VOL. VII. 5 Si EEV. T. K. K. STEBBING OX AMPHIPODA EKOM li'ing-ed with many seta-like spiues ; the finger closely fits the palm and projects a very little beyond it. Second (jnathopods. S . Almost exactly like the first, but the sixth joint rather longer and more slender, -with a smaller palmar tooth, and tlie finger not extending beyond the palm. The marsupial plate is as long as the second joint but much narrower, while the branchial vesicle is considerably longer and much wider ; the side-plate is oblong, m ith the lower margin slightly convex, and like the side-plates in general partly fringed Avitli setoe. Gnathopods. 6 . The species now being described is assigned to Haswell's Urothoci pinguis on the supposition that the account gi\en by Haswell refers to the male, and that in that sex the gnathopods are strikingly different from those of the female. Haswell's description says : — " Gnathopoda large ; anterior pair Avitli the carpus three- fourths of tlie length of the propodos ; the propodos ovoid, swollen ; the palm not defined ; the dactylos half as long as the propodos ; posterior pair longer than the anterior ; carpus small, subtrian<];ular ; ]n'opodos ovate, palm defined by a prominent angle ; dactylos rather more than half as long as the propodos." Third pera'Ojjods. Second joint expanded, longer than broad, front margin sinuous, serrulate, carrying slender spines and setoe, hind margiu smooth ; fourth joint broader than long, with a long free upper margin armed with slender spines, hind margiu cut into 5 teeth, this and the lower margin spinose; fifth joint narrower than fourth, but still very broad, breadth and length equal, fringed with many spines and setai ; sixth joint not longer, and less than half as broad ; finger quite small. i^o^-;-;'/^ j>er^q2;o(/* similar to third, but larger ; second joint broader in proportion to length; fourth very large and setose, with 7 teetli on hind margin, of Avhich the lowest two are formed by deep incisions ; fifth joint rather longer than broad, about twice as broad as the sixth. Fiftliperceopods. The large expansion of the second joint has a smooth front margin, the hind one serrate, the lower sei-rulate and fringed with sette ; the fifth joint is apically finely pectinate; the finger is more than half the length of the sixth joint. Pleopods. The peduncles are short; the rami with about 21 ratlier broad joints. (Jropods. The rami of the first pair are slightly curved, each with a short stout nail ; the rami of the second pair are straight ; those of the third pair (at least in the male) lanceolate, long, plumose. Telson with length and breadth equal, the apices rather divergent, each with a spinule in a small emargination, the outer margins (in the male) setose. Length of male yj inch, of female -^^ inch. " Bondi, New South Wales, cast on the beach during a storm," is the source assigned for the specimen described by Professor Haswell ; the specimen here described was contained in a gathering from Jervis Bay, kindly forwarded to me by the same author. THE COPENHAGEN MUSEUM AND OTHEE SOURCES. 35 Fam. LEUC0TH0IDJ3. Leucothoe INCISA, Robertson. (Plato 10.) 1888. Leucotho'e farina Chcvreux (not Savigny), Bulletin do la Socirte cVetiulcs scientifiqucs de Paris, W annee, U"' sem., Extr. p. 9. 1892. Leucothoe incisa Robertson, Transactions of the Natural History Society of Glasgow, vol. iii. p. 217 (sep. copy, p. 23). The drawings of this species were made many years ago, hut have waited till now for a suitable opportunity for publication. The species of Leucotlioe axe se^iarated by rather fine distinctions. In 18G0 Boeck named a new species LeucofJioe LiUjehorgii, hut in his later works he was willing to let this lapse as a synonym of the long known Leiicolhoii spinicarpiis (Abildgaard). In 18S9 Norman gave the name imparicornis to a form from Shetland, which Sars in 1892 determines to be the same as 'Boeck's I/Hljcborffli,, the latter name having priority. To tliis species, as figured and described by Sars, Leucothoe incisa makes a tolerably close approximation, yet it seems difficult to unite the two. In hicisa tlie fourth side-plates have the front angle rounded, not acute; the first gnathopods have the tip of the process of the fifth joint strongly hooked, the inner margin of the hand not quite smooth but faintly crenulate, and the finger not very small; in the second gnathopods the ^^alm is convex and faintly but broadly crenulate, the finger is not abruptly bent at the base ; the tclson, instead of being little longer than broad, is fully twice as long as broad, with the apex almost acute. As in Lllljehorgil, the inner margin of the wi'ist in the first gnathopods is serrate, and the postero-lateral angles of the third pleon-segment are sharply upturned, forming a sinus with the bulging hind margin. There is a tendencj^ to this in the preceding segment. The mandibles have the cutting- edge divided into about eight teeth ; the secondary plate on the left mandil)le is large, witli ten teeth, that on the right is much slighter (Sai's denies its existence in this genus) ; the second joint of the palp is not much longer tlian the narro'^v^er third. In tli(> maxil- lipeds the first and second joints of the palp have the length and breadth subequal. Length not quite three-tenths of an inch. Taken off Cumbrae, in the Clyde, at low water and also in 20 fathoms, by Dr. David Robertson, LL.D., F.L.S. Anamixis, n. g. Head hood-like. Eirst side-plates small, three following pairs very large. Eyes well developed. First antennae attached below tlie apex of the head, witli elongate peduncle and no secondary flagellum. Second antennae remote from the first, shorter and thinner, Avith small flagellum. Mouth-organs (at least in the adult) degraded and abnormal. Maxillipeds Avith the full number of joints, the third simple. First gnathopods delicately chelate ; second massive, complexly subchelate ; the other limbs slight, normal. Branchial vesicles small, simple. Pleopods small. First and second uropods biramous, third at present unknoAvn. Telson simple. The shape of the head calls to mind the genus Bnlichia, the situation of the antennae Plat ijiscUn opus, the size of the side-plates Metopa, themassiveness of the second gnatho- pods Jlicrojjrotopus, the structure of both pairs of gnathopods and of the antenna) and 36 EEV. T. E. E. STEBBING ON AMPHIPODA FEOM maxillijieds Lencotho'e. In reference to this combination of characters tlie name of the genus has been chosen, from the Greek word ai'a^tgi?, mingling. Among existing families it stands nearest to the Leucothoidse, l)ut the extraordinary nature of the mouth-organs — whether due to a parasitic mode of life or to a marital stage of existence, or falling under any other exiilauation — so far isolates the species now to be described that it may have to be placed alone in a separate family, Anamixidae, which would for the present bear the characters of the genus. Anamixis Hanseni, n. sp. (Plate 11 ) The head is longer than any one of the perseon-segments, and is narrowed distally, Avith rounded apex, with no distinct lateral angles. The second pleon-segment has the postero- lateral angles acute, slightly produced ; those of the third are a little blunted. The fifth segment is very short, scarcely distinguishable from the fourtli ; the sixth projects on either side of the telson, in a way to suggest that the missing third pair of uropods may be of a fairly large size. The eyes are round, placed in the middle of the sides of the head, consisting of about eighteen short ocelli. First antenme. The first joint long and rather stout, the second nearly three-quarters as long as the first, but much more slender, the third about two-fifths of the second ; the flagellum eleven-jointed, a little longer than the first joint of the peduncle. A sensory filament is present on several of the joints. These antennae dejiend from the head, being inserted just below its apex. Second antenntB. These are inserted at the other extremity of the head. The first two joints arc very small, the third is little more than half as long as the first of the upper antennae, the fourth is slightly longer than the second in the other pair, and the lifth is a little longer than the third joint of its own pair. The slender flagellum is four- iointed, less than half as long as the penultimate joint of the peduncle. Mouth-organs. The underside of the head is slightly carinate, and apparently attached to the keel there projects from between the second antennae a vertical plate, which may be called the oral lamina. Its truncate front edge has some minute microscopic teeth. With this curious and abnormal exception, no mouth-parts could be detected other than the pediform maxillipeds. Maxillqjcds. The second joint bulges slightly on the upper or inner side, while on the outer or lower side it has a shallow cleft, between two smoothly rounded apices, which just overlap the bases of tlie third joint. The third joint has no lobe or lamina, but in appearance is the basal joint of a five-jointed palp. Of the actual palp the first and second joints arc about equal in length, tlie second the wider, carrying some setse on the lower margin, the third joint is longer than either of the preceding, armed with several setue, and having its surface minutely furred. The fourth joint or finger is slender, strongly curved, nearly as long as the third joint. Owing to the absence of j)lates from the joints of the protopod the palps are in close contiguity. The appearance is rather that of legs than of mouth-organs. In dissection the head came easily away, leaving the maxillipeds very firmly attached to the first gnathopods. THE COPENHAGEN MUSEUM AND OTHER SOURCES. 37 First gnathopods. The side-plates ave sinall, triangular, with the apex to the rear. The second joint is slender, narrowest at tlie base. The small third joint is larger than the fourth The fifth joint is very much Avider and much longer than the second joint. It may he regarded rather as the hand tlian the wrist, its long and slender curved apical proces«i, tipped Avith a slightly curved needle-like spine, forming the immovable finger of the chela, while the sixth and seventh joints form the movable finger. The sixth joint is slender, i-ather straighter than the process of the fifth, but otherwise very like it, and tipped with a similar spine, which must be regarded as the seventh joint. It might be sujiposed that tlie fifth joint in this remarkable form rejiresented a coalescence of the wrist and liand, did not a com2)arison with the first gnathopods iu Leucotho'e make it reasonably certain that the chela is composed in the way just described. Second gnathopods. The side-plates are very large, rounded in front, produced beyond the first segment. The second joint is narrow, distally somewhat widened, a little curved. The third joint is of stouter build than usual, apparently articulating Avith all the three folloAving joints. The fourtli joint is small, most of it lying flatly on the inner surface of the fifth joint, with which it seems to be in coalescence. The fifth joint is subequal to the second, liut In-oadest at its base and apically pointed. The hand is broad and between three and four times as long as its breadth, the liind margin distally cut into three teeth. The finger, more than half the length of the hand, has a curved acute tip, and two slight projections on the inner margin. The complex clasjier is formed by its impinging against the apex of the Avrist and the denticulations of the hand. The peculiar arrangement of the third and fourth joints may be explained by the extraordinary massiveness of tliese limbs and especially of the hand, Avliich is in striking contrast to that of the preceding pair as well as to the general structure of the other limbs. First 2)erceopods. The side-plates are as deep as the preceding pair, but of much less Avidth. The branchial vesicles are all of remarkably small size. The second joint reaches a little beloAv the side-plate. Of the other joints the fourth is the widest, the fifth is sliorter than the sixtli, tin; nail is slender and curved. Second percBopods. The side-plates are rather Avider than the preceding paii-, with a faint emargination at the farther end of the loAver margin and a very shallow excaA^ation at the upper part of the hind margin. The limb differs but little from the preceding. Third ferceopods. The side-plates are bilobed, Avith the hinder lobe the larger. The second joint is not much longer than wide. The fourth joint has the hind margin slightly produced. The rest of the limb is missing. The spiny armature in these and the other limbs is insignificant. Fourth per ceopods. The side-plates are lobed behind. The second and fourth joints are rather larger than in the preceding and foUoAving pairs. Fifth perceopods. The side-plates are small, rounded behind. The second joint is rather more strongly spined along its front margin than is the case in the other limbs. Fleopods. The rami are small, five- or six-jointed, shorter than the peduncles. JJropods. The first pair are the longer. In both, the inner ramus is a little longer and the outer considerably shorter than the peduncle. Tlic third pair are missing. 38 KEV. T. R. E. STEBBING ON AMPHTPODA FEOM Telson. This is a little longer than broad. The broadly rounded apex does not reacli so far back as the projecting points of the preceding segment, which are in turn overlapped by the peduncles of the second uropods and these by the peduncles of the first pair. The length of one specimen, with tail folded in, was less than a tenth of aa inch, of the other rather more than a tenth. Hab. West Indies. From Goniastrcea varia Dana. The name is given in compliment to my friend, Dr. H. J. Hansen, the accomplished naturalist by whom it was obtained. Pam. PAEDALISCID^. Pardaliscoides Stebl)ing. 1888. Pardaliscoides Stebbing, 'Challenger' Amphipoda, p. 1725. 1893. Pardalisca Delia Valic, Gammarini, p. 691. Pirst antennae longer than second, second joint of the peduncle longer than the first, both flagella many-jointed. Mandibles with broad cutting-edge ; tliat on the left side having two blunt teeth above and two that are acute below, one of them small, the other large, a rather broad accessory plate with crenulate edge, and two plumose spines ; that on the right having a similar cutting-edge miuus the smaller acute tooth, no accessory plate, but three plumose spines ; the three-jointed palp slender, fringed with setiform spines. Pirst maxillte with one seta on the small inner plate, seven very unequal spines on the inner plate, one of them plumose; the second joint of the j^alj) broad, with many spinules about the apical margin. Second maxilbne with the plates slender, the outer carrying three, the inner seven sctse. Maxillipeds with inner plates vei-y small, outer plates short and narrow, fringed with spinules, the supporting joint not very large; j^alp with first joint short, second robust and long, but scarcely longer than the third, the finger long and slender with minute setules on the inner margin. Tlio tritiu-ating organs (anterior lateral gastric lobes) are armed with six long spines. The gnathopods are similar, simple, with the fifth joint robust, fusiform, the sixth and seventh slender, the seventh fringed with minute setules. The peraiopods are slender, elongate. The second uropods have the rami unequal, the third have the rami foliaceous. The telson is deeply cleft. Pardaliscoides tenelltjs Stebbing. (Plate 12.) 1888. Pardaliscoides teneUiis Stebbing 'Challenger' Amphipoda, p. 1~.'25. 1893. Pardalisca abtjssi Delia Valle, Gammaiini, p. G92. Head with acute rostrum. There appears to be a small dorsal denticle on each of the last two or three segments of the pleon. First antenncB. The first joint stout, the third half the length of the second ; of the flagellum thirteen joints remain, the first much the longest ; of the accessory flagellum seven or eight joints remain, the first as long as that of the primary. Second antennce. Last tAvo joints of the peduncle elongate, the last shorter than the preceding; the flagellum half the length of the peduncle, twelve-jointed. THE COPEXHAGEX MUSEUM AND OTHER SOUKCES. 39 Fh'st and second gnathopods. Tliere are numerous spines of vai'ious sizes on and near the margins. On the hind margin of the wrist and hand, commencing at the narrowed distal end of the wrist, is a series of short spines which are plumose. The setules on the inner margin of the fingers are exceedingly small. First and second perceopods. The fifth joint longer than the fourth or the sixth; the second pair rather longer than the first, and further distinguished by having the hind margin of the sixth joint fringed with about a dozen short blunt spines. Third perceopods. Second joint very slightly expanded, fourth joint the longest ; finger slender, acute. Fourth perceopods like the third, but with rather longer joints. Fifth perceopods considerably longer than the fourth, the second joint expanded above, narrowing dovrnward, fourth joint very long. Branchial vesicle small, narrowly oval. Telson much longer than broad, cleft thi-ee-fourths of the length, dehiscent, with a spinule at each apex and a setule on each lateral margin. Length not quite a third of an inch. Kah. South Pacific, lat. 37° 29' S., long. 83° 7' W. Taken by H.M.S. ' Challenger,' in tow-net at trawl, from a depth of 1775 fms. Fam. EUSIRIDJi;. EusiROPSis, n. g. Head distinctly rostrate ; body Avithout dorsal projections ; side-plates of perteon shallow. Antennte of male with calceoli on peduncle and flagelluui in both pairs ; first antennae shorter than the second, secondary flagelluui one-jointed : the second antennae of male with the last joint of the peduncle very elongate. Mouth-organs nearly as in Eitsirus, but the mandibles have the molar feebly developed and the first maxillse have the second joint of the palp narrower and scarcely longer than the first. Gnathopods nearly as in Eitsirus, but with the backward projection of the carpus almost obsolete. Eirstand second peraeopods slender, with the finger ending obtusely and tipped with long setoe. The three following perajopods slender, elongate, plumose, with the fingers acute. The uropods of the first two pairs with outer branch much shorter than inner, the third pair very plumose in the male, the outer ramus shorter than the inner. The telson narrow, apically incised. EusiROPSis RiiSEi, n. sp. (Plates 13, 14.) Head Avith triangular rostrum longer than broad ; second, third, and fourth the shortest of the peraeon-segments ; first three segments of pleon large, with the postero- lateral angles rounded, hind margin not serrate. Eyes to all appearance entirely wanting. First antennce. Eirst joint rather bulky, carrying eight tufts of setules on the lower margin ; second joint rather shorter and much narrower than the first, with calceoli along the lower margin ; third joint almost like a joint of the flagelluui ; the latter rather 40 REV. T. E. E. STEBBING ON AMPHIPODA FEOM stout, carryiug a calceolus on each of tlie thirty-one joints rernainiug, the end being broken ofT. The secondary flagelluin is minute and quite unobtrusive. Second antennce. The first three joints very short ; the fourth stout, not so long as the first of the upper antennae, furnished on the upper margin with nine tufts of setviles ; the fifth slender, longer than the whole peduncle of the other pair, armed above with many calceoli ; the flagellum longer than the peduncle; of the forty-two joints twenty-seven carry each a calceolus on the upper side, the terminal fifteen, which are more slender and elongate than most of the others, having each a sensory filament. It may be supposed that the abundant armature of the antennse compensates the animal for its want of eyes. Tipper lip. The apical margin is rounded, and the usual fringing moustache is strongly developed. Mandibles. As in the neighbouring genus Emirus the cutting-plate is scarcely dentate, the secondary plate on the left mandible is quinque-dentate, on the right it is more spine- like ; the spine-row contains five or six small spines ; the molar is very feeble and unob- trvisive ; the second joint of the palp is robust, tlie third is narrower but rather longer, fringed with many spinules. Lower Up. The inner lobes are smaU. First maxillie. The inner plate is feeble, short, and seemingly not armed with any set£e ; the outer plate carries ten spines, of which the two outermost are the largest, the rest are denticulate ; the palp has a stout first joint, but the second is weak and tapering, scarcely longer than the first, tipped with five setfc. Second maxillce. The inner plate is broader than the outer, but its apical armature is shorter and very scanty. Maxillipeds. The inner plates reach only to the base of the palp, and are not strongly armed, but have the usual apical teeth ; the outer plates reach scarcely to the middle of the palp's second joint, and are fringed with not numerous sctules. The palp's second joint is broad and carries a conspicuous row of setae near the apex ; the third joint is similarly armed ; and the finger, which is long and strong, has a few small setules on its inner margin. First gnathopods. The side-plates are very shallow, covering no part of the limb's second joint. The fourth joint is subequal to the third, its broad apex reaching almost to the base of the hand, and having the wrist attached to its front margin. The dista end of the wrist is attached to the front margin of the hand, not to the side as might be supposed from the drawings made from mounted and somewhat flattened dissections. On the inner side of the wrist there is a small process, probably homologous with the laro-e one in Eusirns which intervenes between the fourth joint and the base of the hand. The hand is massive, distally widened, with long convex palm carrying setules, and endin"- in a spinigerous pocket, into which the long curved finger inserts its tip. Second ynathopods. The side-plates are shallow, longer above than below. The branchial vesicles attached to these and the five following pairs of limbs have accessory lobes. The joints of the second gnathopod show saircely any difference in shape from those of the first. First percBopods. The side-plates have a curious sort of axe-head shape, the front THE COPENHAGEN MUSEUM AND OTHER SOURCES. 41 corner rounded, the hinder acutely produced. The whole limb is very slender, and, like all the other perseopods, is adorned with long plumose setse. The second joint is elongate, with four or five setoe on the hinder margin and two on the front. The fourth joint has four setfe on the front margin; the fiftli has one on the front and two on the hind margin ; the sixth, which is rather longer than either of the two preceding, has two setae of great length on the hind margin and two or three on the front. The seventh joint is not finger-like, less than half the length of the sixth, its apical margin not acute, fringed with six ])lumose sette, mostly of great length. Second perccopods. The side-plates are almost oblong, twice as long as deep, with the upper margin slightly excavate. The limbs are in near agreement with the preceding pair. Third per(E02)ods. The side-plates are bilobed, the hinder lobe the deeper. The second joint is ex23anded, rather deeply notched on the hind margin. The third joint is short. The remaining joints are all very elongate, armed with numei'ous spines and long plumose seta; on both margins, except in the case of the finger, which has the settc only on the hind margin. The fourth, fiftli, and sixth joints are severally much longer than the second, which is scarcely, if at all, longer than the straight acute finger. Fourth percBopods. The hind lobe of the side-j)lates is rather long, the front one evanescent. The limb is like that of the preceding pair, but with a larger second joint, and the fifth decidedly shorter than the sixth. Fifth percropods. The side-plates are not bilobed. ils already noticed, there are branchial vesicles. Tlie second joint is rather longer than in the preceding pair, while the fifth and sixth are not quite so long. As in the two preceding pairs, the setae fringing the margins of the sixth joint are of great length, and the hinder apex carries a remark- able tuft of these elongate appendages, which, together with those on the fingers, produce a striking eff"ect. Fleopods. There are three or four cleft spines on the first joint of the inner ramus, this ramus consisting of seventeen joints, while the outer, which is slightly longer, has nineteen. TJrop>ods. In the first pair the peduncle is nearly as long as the inner ramus, and carries some small plumose setaB on its outer, and spines on its inner margin. The outer ramus is a little more than half the length of the inner. Both have many spines alouo- the margins, those on the inner margin of the inner ramus being small but very close- set. The peduncle of the second pair is about as long as the outer ramus, which is less than half the length of the inner. These rami are armed as in the preceding j)air, which they a little exceed in length. In the third pair the pedimcles rather exceed in length those of the preceding pair. The outer ramus is a little shorter than the inner of tlie second pair; it has spines at six points of the outer margin, and the inner fringed witli spines and many long plumose setae. The inner ramus is rather longer than that of the second pair, and is fringed on both margins with spines and long plumose setae. Telsoii longer than the peduncles of the third m-opods, distally cleft for about a quarter of its length ; a little way above the acute apices a notch on either outer margin carries a long seta, and there is another a little higher up than the top of the cleft. SECOND SERIES. — ZOOLOGY, VOL. VII. 6 42 EEV. T. E. E. STEBBING ON AMPHIPODA FEOM Length, not including the antennae, in the slightly curved position of the sjiecimen figured, two-fifths of an inch. Hab. Tropical Atlantic. The label accompanying the specimen figured contained the words " Eiisei 55. Stud. Sanil. ded. 1892." A second specimen, in less satisfactory condition, was labelled " 22° N.B. 36° V.L. Hygom. Stud. Saml. ded. 1892." Copen- hagen Museum. The specific name was given in MS. by Professor Lutken in compliment to Herr Riise. Pam. undetermined. Sancho, n. g. liostral point small. Perseon depressed, very broad at the centre; fir.st segment short, seventh unusually long. Pleon narrow, much of it flexed. Eyes on the top of the head, separate. First antennae with principal flagellum longer than peduncle; accessory flagellum small, one-jointed. Second antennse with last joint of peduncle longer than the preceding joint. Upper lip not emarginate. Lower lip without inner lobes. Mandibles Avith cutting-edge, accessory plate, and spine-row small, but molar and three-jointed palp powerful. Pirst and second maxillae normal. Maxillipeds with outer plates smaller than, and scarcely reaching beyond, the inner ; fourth joint of palp small. Gnathopods subchelate, the first pair in both sexes feeble ; the second also feeble in the female, but in the male very long with very bulky sixth joint. Pera^opods normal, the fifth pair the longest. Second uropods with peduncle scarcely shorter and rami much longer than those of the first, third with short peduncle but very long inner ramus; in all three pairs the outer ramus is shorter than the inner. Telson short, triangular. The name is taken from a character famous in fiction. Sancho platynotus, n. sp. (Plate 9 A.) The second and third pleon-segments have the postero-lateral angles minutely produced ; at the second segment the pleon is bent and the remainder closely adpressed to the ventral surface of the trunk. Eyes round, separated by more than the diameter of either, composed of numerous ocelli, of which those of the outer ring appear to be larger than the rest. Specimens preserved in spirit have a light pinkish pigment. First antennce. Pirst joint stout, about once and a half as long as broad, second much shorter and thinner, third about half the length of second ; flagellum in male of forty- one joints, the first longer than the last of the peduncle, followed by many joints not longer than In'oad, to which succeed several much longer than broad. Second antennce. The basal joints short, the last joint of the peduncle rather long, longer and thinner than the penultimate, which has an apical tooth ; the flagellum in the male similar in structure to that of the first antenna, but perhaps shorter ; thirty- three joints in an example not quite perfect. Upper lip wath broad front, the margin little curved. THE COPEXHAGEN MUSEUM AND OTHEE SOURCES. 43 Ilatidibles. The cutting-edge small, little dentate, the molar massive; the third joint of the jmlp hroad, distally fringed with spinules. First ma.rillcB. Inner plate oval, tipped with two setse, outer plate with the eleven apical spines very small, inconspicuously denticulate ; second joint of the palp broad, with some apical setules. Second maxillj Sec, Zool. Ser.2 Voi,.VjI.Pl.8. ^^ O prp.5. V '^ Vf TRRSlcbhinij. 'Id prp -i. JTRReid hth ANDAWQTEK G0RPULEKTU5. (THOMSON) CTi: BEING A TfansLinn Soc Zool Ser S.Vol.YII I'i prp5 mji. iOo.'slp. TRRSlebbmg del Pardaliscoides tenellus Stebbing, JTRReidLith OTEDEING, Traws. Ljnn Snc.-ZooL Ser 2 Vol'^/11 Pl 13 -'- Stebbina. del JTRRieihil: Eus.iROPsio RirsEi Nov gen et sp Stebbino Trans Link .joc z.ool 6er c VolVU Pi, H' ft 4 I \ i pi^pi d^J EUSI.ROPSIS KlISEI NOV- GEN ET SP LINNEAN SOCIETY OF LONDON. MEMORANDA CONCERNING TRANSACTIONS. Thel'irst Scries of the Transactions, containing both Botanical and Zoological contributions, has been completed in 30 Vols., and a few entire sets are still for sale. Onl}- certain single volumes, or parts to complete sets, may be obtained at the original prices. 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T/ie Oricfin of the Corpus Callostim : re]iaratioiis stained by Weigert's method, all the observations concerning JS'i/ctojihiltis which are here recorded. ORIGIN OF THE COEPUS CALLOSUM. 51 Perameles nasiita at about the junction of body and descending limb of the lateral ventricle. This corresponds to a situation almost immediately behind the commissures of the liemispheres, as we shall see later. In this section the 'tween-brain — a somewhat square-shaped mass with rounded corners — will be seen to occuj)y the ventral mid-region. The basal part of the thalamic region lies upon the optic tract {o.tr.), which may be seen extending into the furrow between the hemisphere (tlie region of the nucleus amycjdahv, n.a.) and the 'tween-brain. The two halves of the ojitic thalamus are connected by means of a broad bridge of grey matter — the commissura moUis (cm.) — and above and below the latter portions of the third venti'icle may be observed. The small recess of the third ventricle lying above the soft commissure is roofed by a somewhat dome-shaped epithelial fold, which is attached on either side to a ridge containing a longitudinal band of meduUated fibres — the sti'ia medullarls thalami (s.m.t.). Upon its lateral aspect the thalamic region fuses with the corpus striatum of the cerebral hemisphere, and a mass of medulltited fibres, cut either transversely or ol)Iiquely, indicates the place of union. The corpus striatum consists of two parts, which are separated one from another by the internal capsule (ci.). A smaller grey mass, lying above the internal capsule and projecting into the lateral ventricle, is the iiucleus caudatus (n.c). A larger grey mass lying below the internal capsule is the nucleus lentlcularis {u.L). The ventral part of the nucleus lenticularis [n.a.) is the homologue of the grey mass known in human anatomy as the nucleus mnygdalce. It is directly continuous with a cortical area of distinctive structure known as \hQ liyr'iform lobe [i^y.l.), from which the nucleus lenticularis in its upper part is separated by a layer of meduUated fibres (the external capsule, c.e.). Along its dorsal border the pyriform lobe is separated from the general cortex (which Turner calls "pallium," p.) by the shallow rhinal fissure {f.r.). Above the corpus striatum, where the lateral wall and roof of the ventricle are formed by this general cortex ov pallium, the inner lining of the latter is formed by a mass of meduUated fibres — the corona radlata {c.r.) of writers. If the cortex be traced in a mesial direction its edge wUl be found to present those peculiarly distinctive features which w^e at once recognize as hippocampus. Thus if the mesial waU of tlie hemisphere be traced down- ward in the section (fig. 1, PL 15) we reach a deep indentation — the hippocamptal fissure , and corresponding to this fissure a marked prominence into the lateral ventricle forming the hippocampus {hip.). Below the hippocampal fissure the characteristic features of the fascia dentata (fd.) (Avhich we shall consider subsequently) are immediately recognizable. And extending into the deep depression between the nucleus caudatus {n.c.) and optic thalamus is the prominent _^mir/ff (fi-), spur-like in transverse section. [In order to avoid an luinecessary confusion in the figure, the choroidal fold of the lateral ventricle which is attached to the fiml)ria has not been represented.] Having thus seen how the " hippocampal formation " constitutes the edge of the cortex cerebri, I propose to carefully examine the series of changes whicli this peculiar formation undergoes as we trace it forward in a series of coronal sections of the cerebrimi of the bandicoot (Perameles). 52 DK. G. ELLIOT SMITH ON THE A coronal section tlirongh the cerebrum, just in front of that represented in the first figure, presents a marked change in the appearance of the hippocampal region, Avhich is represented upon an enlarged scale in fig. 2. The hijipocarapus itself, as well as the fascia dentata, have undergone practically no change, but a huge bundle of medullated fibres from the upper part of the fimbria is now exposed in the act of crossing the middle line. This is the posterior exti'emity of what — to avoid confusion of terms — will for the present be termed the commissura dorsalis (c.i).). It would be foi-eign to the scope of this work to descril)e in detail the histology of the hippocampal formation, seeing that the minute structure of the Metatherian hippocampus is identical with that of the Eutherian, which Sala, Schaff'er, Ramon y Cajal, and von KoUiker*, among many others, have so carefully and minutely described Avithin recent years. But I wish to call attention to certain features which are intimately associated with the evolution of the structure we are primarily considering. Lying upon the upper surface of the " dorsal commissure " (c.d.) there is a complicated epithelial fold the outline of which is roughly triangular, and which projects upward into the great cleft between the two cerebral hemispheres. The fascia dentata {f.d.) lies in contact with this epithelial (choroidal) fold on either side, and may be easily recognized by certain distinctive features. Thus it possesses a very thickly -packed column of small cells — the stratum gramdosum (s.fjr.) — the nuclei of which stain very deeply, lying parallel to the surface, from which they are separated by a clear layer almost devoid of cells — the stratum molecuJare. The fascia dentata — consisting of stratum granulosum and stratum moleculare — is folded in a peculiarly characteristic manner. Its mesial extremity is completely bent upon itself, so that the stratum moleculare or superficial layer rests upon the dorsal aspect of the dorsal commissure. The lateral extremity of the fascia dentata undergoes a corresponding bending, the concavity of which is directed toward the mesial plane. It would appear that the fascia dentata had continued to increase in breadth whilst its mesial and lateral extremities were relatively fixed, and, to accommodate itself to tliese conditions, it bad bulged out into a pouch, as it were, and at the same time become flattened by the resistance of the general cortex lying immediately above it. Such factors, in reality, seem to have been at work, as I have recently pointed out t. The fissure which separates the fascia dentata from the general cortex where their resj^ective superficial layers come into contact is ihefissura hipiMcampi (f.h.). The concavity of this pouch of fascia dentata is occupied l)y scattered nerve-cells, many of which give origin to the brush of medullated fibres which are to be seen in the figure, collecting near the inner margin of the fascia dentata, to lose themselves in the huge mass of medullated fibres lying immediately below. The hippocampus proper projects as a large rounded swelling into the lateral ventricle. This swelling is covered by a thick layer of medullated fibres — the so-called ulceus (alv.). These fibres almost all pursue an obliqiie course, so that in a coronal section only short pieces of ^fibre are seen massed together. In the first figure most of the fibres of the * ' Gewebelehre des "Munsohen,' Bd. ii. zwciter Hiilt'te, IS'JG. t '■ The Fascia Dentata,"' Auatomischer Aiizeiger, xii. Bd. Nr. 4 iind .5, 1895, p. 119. OEIGIN OF THE COEPUS CALLOSUM. 53 alveus are tending towards the fimbria, but in the section under consideration many fibres of the alveus, as well as fibres coming from the " pouch " of the fascia dentata, proceed directly into the commissura dorsaUs along with many fibres of the fimbria which have come from more caudally situated regions of the hippocampus. It will be noticed, however, in the figure that as yet only the upper part of tlie fimbria is contributing fibres to the commissure. The tip of the fimbria, which contains fibres coming from the most distant parts (temporal pole) of the hippocampus, is yet undisturbed and has given no contriluition to the dorsal commissure. Between the alveus and the curved lateral part of the hippocanipal fissure there is a broad, more or less definitely stratified region. Slightly nearer to the alveus there is a very uniform and clear layer (in specimens stained by Weigert's method). This is the layer of " ^lyramidal cells," and consists of a closely-packed column of large cells, which stain moderately with ordinary stains. Between the layer of pyramids {i^yr.) and the alveus {ctlo.) there is a stratum containing scattered polymorphous cells and very abmidant medullated nerve-fibres — the layer of poli/morphous cells. The space between the hippocamjjal fissure and the layer of pyramids is usually divided by writers into three zones — a broad clear layer next to the layer of pyramids [stratum radiatum, s.r.), a thin superficial layer [stratum zonale), and an intermediate layer very rich in medullated nerve-fibres [stratu^ii lacunosum, s.l.). A large number of fine medullated fibres (.r) extend from the region of the layer of pyramids through the stratum radiatum into the stratum lacunosum. These fibres are very distinct in the region bordering upon the fascia dentata [clde fig.). In the stratum lacvmosum many of these fibres end by means of free branching in relation to the processes of the pyramidal cells, which extend through the stratum radiatum into the more superficial regions. But a considerable number of medullated fibres assume a longitudinal direction (/. e. in the long axis of the hippocampus) as soon as they reach the stratum lacunosum [s.l.). These fibres, which may 1)e called " longitudinal association fibres of the hipjwcamj^us," appear in transverse section [s.l.) as rounded bundles immediately surrounding the lateral or deeper part of the hippocampal fissure. In the general cortex [j).) the cells are scattered throughout the whole thickness of the cortex, whereas in the hippocampus (leaving out of account the fascia dentata) the great majority of the nerve-cells are crowded together into the regular row of pyramids. The transition-region from typical cortex to typical hippocampus is generally known as the sub/culuv/, cornu animonis [sub.). AVhether the " subiculum" ought to be grouped with the general cortex or with the hippocampus is a question to which Ave shall have to refer su.bsequently. The deej)est layer of the general cortex consists of a mass of medullated fibres — the corona, radiata. It will be noticed at a glance that while the fibres derived from the hippocampus and " subiculum " proceed into the alveus, those derived from the general cortex proceed away from the alveus, i. e. towards tlie external capsule. At the point of meeting of alveus and corona radiata there is obviously a commingling of fibres, but it is equally clear that any passage of fibres from the alveus into the " corona '' or vice versci is either non-existent or extremely slight and practically negligible. In the adjoining regions there are groups of longitudinal fibres belonging respectively to the two distinct formations, and it is quite possible that an interchange between these two 54 DE. G. ELLIOT SMITH ON THE series may take place. The longitudinal series belonging to the margin of the general cortex or pallium is the so-called cingulum of higher forms (figs. 6 & 11, cing., clngJ). There are, however, definite bonds of union between hippocampus and general cortex which are found in their junction. Thus from the stratum zonale and stratum lacunosum of the hippocampus fibres extend not only into the " neutral ground," so to speak, of the " subiculum cornu ammonis " but well into the molecular layer of undoubtedly true cortex. This is a definite association bundle between hippocampus and pallium, which may be called tractus hippocamfi ad pallium, (fig. 2,?/). As the hippocampal region is successively examined in a series of coronal sections, the main features of the hipj)0campal formation itself remain imchauged for some time, but its commissure — the commissura dorsalis — undergoes marked changes. Thus the depth of the commissure rapidly increases at the same time that the prominence of the fimbriae is diminishing (fig. 3). The meaning of this is that an increased number of fibres from the fimbria are crossing in the dorsal commissure. The scheme (fig. 1) of the commissures as they are seen ia sagittal section explains the meaning of these changes. In figure 5 a new factor for the first time becomes evident. Upon the lateral aspects of the commissure, more especially upon the right side of the figure, a mass of grey matter {s) will be observed to enclose the dorsal commis.sure and to become continuous ventrally with a mass enclosing a second commissu.re — the commissura ventralis. This grey mass enclosing the two commissures will for the jiresent be distinguished as the " commissure-bed." On either side it will be noticed to become continuous by a narrow bridge of grey matter with the corjms striatum (est.). In this narrow bridge there are a number of longitudinally-coursing nerve-fibres (s.t.). These are the uncrossed fibres of the stria ter'minalis, the other fibres of which may l)e seen entering the ventral commissure {s.t!.) in figure 3 to cross to the other side. In figure 5 the dorsal commissure has reached its greatest depth. Figure 6 shows the appearance which is presented by a section after all the commissural fibres of the fimbria have crossed. The thin commissura dorsalis (c.d.) is derived from the corresponding region of the hippocampal formation. The huge commissura ventralis (c.v.) appears to become continuous with the capsula externa [ce.], which, after being joined by fibres of the capsula interna (cL), becomes the corona radiata. The dorsal and ventral commissures lie in the large mass of grey matter which forms the commissure-bed. A thin lamina (?') of this grey mass may sometimes be distinguished upon the dorsal as^jcct of the commissura dorsalis. This may be distinguished as the " indusium vertim." The " commissure-bed " (s) contains large numbers of uncrossed fibres (d.f.), which are derived from the alveus of the hippocampus (which is situated above them) and from the fimbria. These fibres are divided into two groups by the ventral commissure. The p)ostcommissural fibres (columna fornicis, c.f.) collect upon the dorsal aspect of the ventral commissure and incline backward and downward to enter the thalamic region. The precommissural fibres proceed downward and forward in front of the ventral commissui'e. OEIGIN OF THE COEPUS CALLOSUM. 55 As we proceed forward in tlie examination of coronal sections, the dorsal commissure will be found to become gradually thinner and finally disappear altogether, while the desceudmg foniix-fibres remain unchanged. The ventral commissure disappears in about the same coronal plane. The " commissw^e-hed " extends a slight distance further forward before the hemisplieres become separated one from another. Pigure 7 represents (about four times the natural size) the appearance of a coronal section immediately in front of the place where the hemispheres become separated from each other. In this figure the hippocampus is again easily recognizable, although its conformation has become greatly simplified. The fissura Idppocampl (f.h.) is much shallower, and the hipj)Ocampal projection into the ventricle less prominent. The fascia dentata is much narrower, and consequently much less folded. The thin alveus may be seen proceeding directly into the mass of desceudinfj forwix-fihres which occupy the superficial portions of the grey mass which we may call the " corpus prcecominissiiralc" *, but which is really only the anterior continuation and homologue of the grey mass which further back has been called " commisstire-bed.'" The other features of the section do not concern us in considering the hij)pocampal formation. The only other point to which I wish to call attention is tliat the " corpus prcecommissurale " is directly continuous below the lateral ventricle with the corpus striatum, where the latter is capped by the peculiar cortex which Ganser calls the " cortex of the head of the corpus striatum," and which corresponds to the " tubei'culnm olfactorimi " [t.o.) — such a prominent feature upon the ventral aspect of this brain. If we were to trace these various structures forward in a series of coronal sections, we should find that the hippocampal fissure would become gradually shallower until it eventually disappeared, the prominence in the ventricle disappearing pari passu. The fascia dentata, now placed entirely upon the surface, becomes narrower and less clearly differentiated, until at last we fail to recognize any distinguishing feature of a hippo- campus. But by the time this has occurred we have arrived almost at the olfactory pedvtncle. In certain Marsupial brains {Dasyuriis clverrinus) it is even possible to distinguish the hippocampal formation as far forward as the olfactory peduncle, so that here wo have the "precommissural area " completely cut off from the general cortex or pallium {p.) by a hippocampal band, as semi-schematically represented in figure 8 {hip." & f.d.). This is the primitive condition of the hippocampus, which is found (although recognized with difficulty) in the Reptile, and which I have already described in the fcetal OrnithorMjnclms (Qu. Join-. Micr. Sci. vol. xxxix. pp. 181-206). Pigure 9 represents the appearance which this region presents in Perameles when viewed from its mesial aspect. In this figure the optic nerve (opt) is seen extending towards the lamina terminaHs, at the inferior extremity of which is the oval section of the optic tract (o.tr.). Extending upward from the optic tract is the thin ventral portion of the lamina terminalis' — the lamina cinerea {I.e.). At its upper part this lamina expands to enclose the large * By " corpus pnicommissunde " is meant that grey mass the mesial surface of which is the "precommissural area " (p.a.). SECOND SERIES.— ZOOLOGY, VOL. VII. 9 56 DK. G. ELLIOT SMITH ON THE commissura veiitralis (c.v.), oval in section and placed obliquely. Extending upward from the ventral commissure there is a thick mass of grey matter — the "com- missure-bed'" {s) — Avhich contains in its upper part the commissura dorsalis (c.D.), shaped somewhat like an inverted obliquely placed V Avith the dorsal limb nearly horizontal. Above the dorsal commissure the fascia dentata {f.d.) is easily recognizable and is separated from the general cortex (jk) by the fissura Mppocamjpi {f.h.). Anteriorly the hippocampal fissure gradually becomes shallower until it can no longer be traced, so that the fascia dentata, the stratvim zonale of the hippocampus, which now of course lies upon the surface (compare figure 8, hip.'"), and general cortex {p.) are indistinguishable. Upon its ventral side the fascia dentata becomes directly continuous with the extensive pale region which constitutes the " frecommissnral area" (p.a.). In the forward direction the "• precommissural area " is directly continuous with the mesial wall of the extremely short olfactory peduncle, which connects the hemisphere with the olfactory bulb {o.h.). Upon its ventral side the " precommissural area " becomes continuous with the grey boss generally known as the " tuherctihtm oJfactorinm " {t.o.). By means of this representation of the anterior portion of the mesial wall of the hemisphere of Ferameles (fig. 9), and the semi-schematic representation of the corre- sponding region in Dasyurus (fig. 8), we obtain a good general idea of the anatomy of the commissural region. In Dasyurtis it will be observed that the dorsal commissure is not so distinctly bilaminar as it is in Pe/'flrtK'/fs : and in Phascolarctos (PI. 16. fig. lOj it can hardly be called bilaminar. Thus we have in the Marsupial all the intermediate stages between the rounded dorsal commissure of Oriiithorhynchiis and Echidna and the distinctly bilaminar form found in most mammals. There are certain important features of this region which can only be demonstrated by sagittal section, which we will consider almost immediately. But before leaving the consideration of figure 8, I wish to call attention to the possible consequences of elongation of the commissura dorsalis. The " commissura dorsalis " is contained in the mass of grey matter which I have called the " commissure-bed," the separate anterior prolongations of which in the two hemispheres are formed by the '^corpora j^'^ffcommissuralia'" — the grey masses corresponding to the surface-region of each hemisphere, which is distinguished as "precommissural area." Now this combined grey mass — " commissure- bed" and " corpus prnecommissurale "■ — is separated from the general cortex (pallium) above it by tlie hippocampus ; and the dorsal limb of the commissure separates the " commissure- bed " from what we may call the " supracommissural hippocampus," while the " corpixs prsecommissui'ale " becomes directly continuous with wdiat we may call tlie " pre- commissural hippocampus." Now it is clear that if the dorsal commissure elongates in the forward direction it must cut otf jiart of this " precommissural " body from the precommissural hippocampus, which becomes " supracommissural." The structure lying upon the ventral aspect of such an elongated dorsal limb of the commissura dorsalis must be either " commissure-bed " or " corpus pra^commissiu'ale." ORIGIX OF THE CORPUS CALLOSUM. 57 Figure 10 represents the appearance of a sagittal section through the corresponding region in the brain of Phascolarctos clnereus, after stciining hy the Weigert method. Between the small commlssiim dorsalis (c.n.) and the large elliptical commissura ventmlis (c.v.) a large number of non-crossing fibres will be noticed in the " commissure-bed " and "precommissural area." Of these the postcommissural form the columna fornicis (c.f.). The precommissural area contains various sets of fibres. The largest group (a) connect the alveus hippocampi and the basal region of the brain just behind the tuberculum ■olfactorium (f.o.). In Oniif/ior/n/ncf/iis I distinguished these fibres as the " hippocampo- basal association bundle" *. Other fibres (/3) pass backward below the ventral commissure to enter the subthalamic region, wliere they become lost. Fibres entering into the constitution of these tAVO series may be seen in the jjrecommissural area (in the region marked jj.«.), proceeding from the most anterior i)art of the hijipocampus. Fibres may also be seen proceeding directly from the olfactory peduncle (and probably bulb) to enter the fascia dentata (f.d.). This is the olfactory bundle of the fascia dentata (y). Other fibres belonging to the same series (o) may be seen proceeding backward above the dorsal commissure as a well-defined tract, probably homologous with the nerve- fibres of the stria medialis Lancisli of the higher mammalian brain. In the Marsupial, a typical hippocampal formation lies upon the dorsal aspect of the commissura dorsalis. In tbis hippocampal formation there are two important series of longitudinal fibres, Avhich are displayed most clearly in a horizontal section. Such a. section of the cerebral hemisj^here of Trlchosurns culj)ecula is represented in fig. 11. In this figure (as also in fig. 2) a large series of longitudinal association bundles are visible in the stratmii lacunosum. Secondly, in the region of the subiculum (and possibly in other regions of the hippocampus) large numbers of longitudinal fibres are contained in the alveus, but in transverse section are not recognizable in the mass of oblique fibres. Upon the ventral aspect of the hippocampus in its anterior part we have had occasion to refer to a large mass of grey matter, the anterior paired region of which we have known as the " corpus prsecommissurale," and its posterior region as the " commissure-bed." This region has been the great source of confusion to comparative anatomists, more especially those working at rej)tilian and amphibian forms, and it therefore demands a very careful study. Most writers call the whole mass the " septum." A study of figs. 5, G, and 9, which are all from Perameles, shows that the " commissure- bed," or matrix of the commissures, extends across the median plane uninterruptedly, becomes continuous upon its dorsal aspect with the hippocampus of both sides, and upon its ventral aspect with that thin band {I.e.) of the lamina terminalis which extends from the ventral commissure to the optic tract (o.tr.). It is connected also in the median line above with the thin epithelial roof of the third ventricle (a structure not sho^^ n in the figures). It is clear, therefore, that this matrix, which includes the two commissures, occupies the situation of the dorsal part of the lamina terminalis, and in part bomids the third ventricle anteriorly. * Journal of Anatomy and Physiology, vol. xxs. p. 480. 58 DR. G. ELLIOT SMITH ON THE If we examine a series of transverse and sagittal sections of a reptilian brain, it will be found that both ventral and dorsal commissni-es lie in the easily recognizable lamina terminalis. This lamina contains in the median j)lane a minimal amount of grey matter. But on either side of the median plane this thin bridge of grey matter becomes continuous with a huge mass of grey matter which we readily recognize as the backward continuation of the " precommissural body." Thus in the Reptile the " commissure-bed " consists of the posterior extremities of the " precommissural arese " united by the thin grey lamina formed by the lamina terminalis. In the mammal it is evident that either the grey mass of the " precommissural area" has invaded, and thus thickened, the lamiua terminalis, which liecomes a continuous grey mass across the mesial plane, or, on the other hand, the mesial surfaces of the two posterior regions of the precommissural area may have become " glued " together. One or other event must have occurred ; and the evidence, I believe, points to a gradual thickening of the lamina terminalis by the invasion of grey matter from the adjacent " precommissural area." However the thickening is brought about, we know that the two cei'ebral commissures of the Marsupial lie in the " commissure-bed," which is morphologically a thickening of the lamina terminalis. Yet we are equally sure, both from its topographical relations to surrounding structures and from its minute structure, that the " commissure-bed " is morphologically part of the same sheet of grey matter as the " precommissural area." If the hippocampal region be studied where it bulges in the descending limb of the lateral ventricle in any Eutherian brain, a considerable variety of the form and relative sizes of its constituent parts will be apparent. In the Marsupial brain equally great variations are found in the corresponding region of the hipj)ocampus. But if we examine the supracommissural part of the hippocampus in a series of Marsupials, the greatest variety and most varied degrees of complexity are demonstrated. In Notoryctes, and less markedly in Dcmjiimis, the formation is very simj)le. In Ilacropus it is much more complex. Perameles is an example of a highly-developed type. Both Monotremes present in the supracommissural region a more complicated form of hippocampus than is fovmd in any other mammal. But the anterior extremity of the hippocampus undergoes the same process of unfolding and simplification in all Marsupials and Monotremes which I have so briefly described in Ferameles. Hence, should we find a difference in the relative degree of development of various parts of the hippocampal formation in the brains of two different animals, we must not lay much weight upon such differences as an indication of the systemic position of their possessor. The Mippocampal Region in the J3at. The cerebrum of the bat may now be studied in the same manner as that of the bandi- coot. Beginning with a coronal section through the hippocampal region of Miniopteriis immediately behind the region of tlie commissures, one cannot fail to notice the great similarity between the two forms (figs. 12 and 1). What differences do occur, apart from those of al)solute size, point to a less complex form of structure in Miniopterus (fig. 12) than in Perameles (fig. 1). This simpfication consists of a diminished depth of OEIGIN OF THE CORPUS CALLOSUM. 59 the hippocampal fissure [f.h.), a less prominent hippocampal eminence in the lateral ventricle, and a less broad and slightly less convoluted fascia dentata {f.d.). These variations in the form of the hippocampus are of little moment, for, as I have before remarked, great variations are found in any order. Moreover, it is noteworthy that in very small Marsupials like Notoryctes one finds a simplicity of hippocampal formation similar to that which the miniite Miniopterus presents (compare fig. 6 of my paper on Notoryctes*). In the next section, whicli passes through the posterior extremity or splenimn of the dorsal commissure (PL 16. fig. 13), we have a condition which recalls that presented by the corresponding section through the brain of Perameles (Pi. 15. fig. 2). But if we compare the hippocampus in figs. 12 and 13, a distinct simplification will be noticed in the foremost section (fig. 13). The fascia dentata (f.d.) is narrower, the layer of pyramidal cells {pyr.) is shorter, and the hippocampus as a whole is distinctly flatter. In fig. 12 there is a very sharp angle between the alveus and tlie corona i-adiata, while in fig. 13 the angle has become rounded otF. It is possible that fibres coming from a wider cortical field may round off the angle, but the carmine stain does not permit us to definitely decide this. But in the next section (fig. 11) there is no question, even with the carmine stain, of the much wider field of origin of the dorsal commissiu'e. If we are undecided whether any fibres other than hippocampal are passing to the dorsal commissure in fig. 13, we have in fig. 11 a very distinct demonstration of the existence of a verv considerable bundle of fibres arisina: from the sjeneral cortex and forming part of the superior commissure. In fiict, the insignificant flattened band of grey matter which now represents the hippocampus can contribute but a very small share towards the formation of the thick commissural tract (c.D.) upon which it lies. The hippocampus is now much more insignificant and more flattened than it was in the last figure. The regular row of nuclei immediately above the dorsal commissure belongs to the layer of pyramidal cells of the hippocampus {pyr.), and the group of closely- aggregated smaller nuclei which cap the mesial end of the layer of pyramids represents the stratum granulosum of the fascia dentata. In fig. 15 the region of the fascia dentata from fig. 11 has been rei)resented upon a larger scale, and in figs. 12, 13, 11, and 15 the stratum moleculare of the fascia dentata has been shaded in order to render its recognition more easy. It will be noticed, if we comj^ai-e figs. 13 and 11, that the commissural fibres of the general cortex pursue their new course through the alveus of the hippocampus. In other words, the alveus of the " dorsal hippocam^nis " of the bat consists of a mixture of fibres derived from the hijijiocampus, which we might call " true alveus," and commissural fibres derived from the general cortex — "false alveus." Our "false alveus " is the corpus callosum proper. Prom the examination of this series, therefore, we may infer that the fibres of the corpus callosum proper reach the mesial platie by passing through the alveus of the dorsal part of the hippocampus. * " The Cerebrum of Notoryctes tupldops,"' Transactions of the Eoyal Society of South Australia, vol. xix. pi. viii. (1895). 60 DE. G. ELLIOT SMITH ON THE As we proceed forward the supracommissural hippocampus becomes more and more rudimentary. Had we not been tracing- these structures in a series of sections, we should never recognize in the few cells situated above the commissures in fig. 16 the representatives of the fascia dentata {f.d.) and the rest of the hippocampus i])^)'.). If we were to examine a series of sections further forward we should find, after the anterior extremity of the dorsal commissure had been passed, that at the junction of the precommissural area and general cortex (pallium) a few small cells would be found to represent the hippocampus which is present in the marsupial (fig. 7). Now that we have seen how the hippocampus is disposed in transverse sections, it will complete oiu* ideas concerning the commissural region if we study its disposition in sagittal section. The transverse sections wliich I have figured were those of Jliniojpterus. The two series of sections of the brain of Nyctophilus, which would have served our purpose even better, were not exactly transverse, and therefore might be confusing. It may be remarked, however, that the " iion-hippocampal " element in the dorsal commissure is even less developed in Nyctophilus than it is in the single specimen of Minioptcrus which I have examined. I have made several series of sagittal sections of the brain of Nyctophilus, and, for illustration, a section slightly to the side of the middle line has been chosen in order to show the relation of th(; hippocampus to the " splenium " of the dorsal commissure, A section passing through the mesial plane presents no difi'erence in the appearance of the commissures from that presented in fig. 17. In this section (fig. 17) we cannot fail to be struck with the resemblance to the Marsupial. The relatively enormous size of the ventral commissure (c.v.) and the shape and proportions of the dorsal commissure (c.D.) are strongly suggestive of the Metatherian structures. Yet in no Marsupial are the two limbs of the commissure so broadly expanded. For the ventral limb (c.D.") is nearly vertical, and the dorsal limb (c.D.') nearly horizontal, so that the angle included between the two limbs is not far short of 00". Of the two lim1)s the ventral is the larger. Both limbs become thicker as they are traced towards their place of union, where they form a massive " splenium." Immediately behind the splenium in this section we see the fascia dentata {f.d.) cut very obliquely, and extending forward from the concavity of the pouch formed by the stratum granulosum the layer of pyramidal cells of the hijjpocampus {hip.) immediately above the dorsal commissure. The " commissure-bed " (s) enclosing both commissures fills up the great interval between the two limbs of the commissura dorsalis and tlie commissura ventralis. In the dorsal limb of the commissura dorsalis (c.i).') I have represented by means of dots the position which a study of transverse sections leads me to regard as approximately those occupied by the commissural fibres which do not spring from the hippocampal formation, i. e. by the fibres of the corpus callosum proper. From this we see that the anterior extremity of the dorsal limb is almost purely " callosal " — if we may use such a term. The transition from pvirely " callosal " to purely " hi2)i)ocampal " parts of the commissure is a very gradual one, " hippocampal " and " non-hippocampal " fibres being intimately mixed one with another at the place of junction. ORIGIN OF THE CORPUS CALLOSUM. 61 Tims it icould appear that in this bat cominissural fibres arising from a very restricted area of the dorso-mesial cortex above the supracommissural region of hippocayrtpus, instead of passing by the circuitous route via the external capsule and through the ventral commissure, pass through the alveus of the supracommissural hip)p)Ocampus to reach the opposite hemisphere through the dorsal limb of the dorsal commisstire. In other icords, fibres tohich do not c. /. F/c.Z F/a Fig. 1. — Scheme to show the arrangement of the hippocampus in the mesial wall of the hemisphere of a Marsupial. The darkly-shaded part represents the first corpus eallosum, such as is found in Miiuojjtenis, and the arrow indicates the Une of its backward extension in the higher Mammals. Fig. 2. — Scheme of the corresponding region of a more highly developed cerebrum, such as that of Pteropus. Fig. 3. — The " spherical " region from fig. 2 on a larger scale. remains of the hippocampus which cover the dorsal aspect of the corpus eallosum are stretched, and thus further attenuated, by the lengthening commissure. The backward growth of the commissure, owing to its obliquity, soon indents the hippocampal formation just at the junction of the atrophic " supracommissural " segment with the SECOND SERIES. — ZOOLOGY, VOL. VII. 10 64 DE. G. ELLIOT SMITH ON THE uaaltered " postcommissural " segment. This indentation soon increases and becomes a very extensive bend, the portion of the hippocampus which surrounds the posterior extremity of the dorsal commissure being carried backward and greatly stretched (fig,. 2). In this way the obliquely-directed commissure fi.rst of all pushes upward and backward the hippocampus at the junction of supra- and postcommissural parts, stretchiug and carrying back the part of hippocampus that invests it above the rest of tlie j^ostcommis- sural hippocmnpus. The " postcommissural hippocampus " (fig. 3, hip) thus appears tO' become subcallosal and to be separated in the vertical plane from the splenium of the dorsal commissure {s})!) and the circumsplenial portion of the hippocampus {hip') by a process of pallium (figs. 2 and 3, *) ujjon which Zuckerkandl has laid so much stress under the confusing name " Balkenwiudvmg." (It will be remem1)ered that it was the lack of this feature which, in part, led him to group a bat with Marsupials and Monotremes). As a result of the operation of the above-mentioned factors, therefore, a somewhat reversed S-shaped bending is produced in tlie hij^pocanipus at the jimction of its middle and posterior segments. The upper part of the S with its concavity looking forward is formed by the attenuated hippocampus (fig. 3, hip') surrounding the splenium (fig. 3, spl), while the lower part of the S, which is convex in front, is formed by a " sul)splenial " bending of a plumper hippocampal region, whicli I have distinguished as the " hippo- campal flexure " {fl^c)- Throughout all these changes tlie main mass of the ventral limb of the dorsal com- missure (CD.") has remained unchanged. In the Marsupial and in a large number of lowlier Eutheria the plump ventral limb extends obliquely upwards to meet the dorsal limb in a thick splenium. But when the dorsal limb extends further l)ackward, the main mass of the ventral limb is left in its old position (fig. 2, c.d."), its postero-supcrior extremity becoming greatly stretched and correspondingly thinned by tiie backwardly-extending corpus callosum. The fimbria maintains its position unchanged (figs. 1 and 2,_7^") and always lies upon the posterior or inferior aspect of the corpus callosum. In its backward growth the corpus callosum carries back its matrix or " commissure-bed," in which it always lies. But although the elongation of tiie corpiis callosum is most obvious in tlie backward' direction, it also groA^ s forward towards the anterior extremity of the brain. In the Amphibia and certain Reptiles, Avhere the olfactory bulb is placed in front and is not overlapped by the hemisphere, the " corpus prgecommissurale " extends forward as a horizontal baud from the lamina terminalis to the mesial wall of the olfactory peduncle.- It is bomuled upon its dorsal aspect by the homologue of the hippocampus. In the Marsupials with small pallia the upper margin of the precommissural body is slightly oblique (PL 15. figs. 8 and D). As the pallium increases in extent it bulges over the olfactory bulb (figs. 1 and 2, p. 63) more and more, and consequently the " precommis- sural " hippocam])Us {hip") becomes more and more oblique, because it always extends towards the olfactory peduncle. Thus the hippocampus comes to bend downward iu; front of the commissures. Now it is obvious that the dorsal limb of the commissura dorsalis (fig. 1), if it extends forward, must indent this precommissural segment of the OKIGIN OF THE CORPUS CALLO.SUM, 65 hippocampus as I have represented in fig. 2. This anterior portion of indented hippo- campus is the "gyms grnicuW' of Zuckerkandl. It is ai:)parent from this that the dorsal comiiiissure, which in. the Ilarsupial liesroithin a well-defined arc formed by the hippocampus (fig. 1), never breaks through this hippo- campal arc even in its much more extended and reconstructed form as a corpus callosum, but pushes the dorsal part of the arc before it as it elongates in. both directions (fig. 2). We have seen that in tlae Marsupial a large mass of grey substance, containing both commissures and formed by the "corpus prfecommissurale " and "commissure-bed," is situated i;pon the ventral aspect of this hippocampal arc. Since the hijipocampal formation may be recognized surrounding the corpus callosum even in the brains of the ox, the monkey, and man, it is clear tliat the matrix of this commissure can be formed of no other structure than the " precommissural body " and the " commissure-bed." This introduces us to the problem of the nature of the " septum pellucidum." We have already seen that the first " callosal " fibres rej)lace the hippocampal fibres of the dorsal limb of the " commissura dorsalis," and in every respect joresent the same relations as the fibres, the places of which they usurp. The first " callosal " fibres, therefore, must lie in the structure which is exactly homologous to what we have called, in the Marsupial, the " commissure-bed." In discussing the natiu"e of the " commissure-bed " we came to the conclusion that with the increasing dimensions of the commissures the dorsal part of the lamina terminalis became thickened or invaded by the posterior parts of the " corjjora prte- commissuralia," so that a bridge of grey matter — the " commissure-bed " — was formed, connecting the two hemispheres, and forming a matrix for the two cerebral commissures. This secondaiy thickening appears to take place gi-adually in the ontogeny of each individual, and cannot be regai'ded as a mere mechanical fusion of the precommissural areoe of the two hemispheres. We may therefore safely say that the dorsal commissure of the Metatherian and (for the reasons stated aljove) of the early Eiitherian cerebrum is contained in a matrix which is formed by a thickening of the dorsal part of the lamina terminalis at the expense of the " corpora praecommissuralia." As new commissural fibres crowd in aud the commissure increases ia length and depth, this matrix becomes extended, but I believe it always continues to enclose the dorsal commissure, even in its most extended form. Paul Martin says tha in the cat the cephalic extremity of the corpus callosum or genu is formed by the apposition of fibres in front of those which are situated in the thickened lamina terminalis. It must be evident (if we glance at fig. 1) that if these apposed fibres grow in a " secondary fusion of the walls of the hemisphere," such a fusion must consist of a " soldering " of the two "precommissural hippocampi" {hip"). But such a " soldering " does not take place, because in the gyrus genicuU we have seen the representative of the " precommissural " hippocampus pushed before the advancing corpus callosirm. There seems to be no other .alternative which could be for a moment maintained but that the corpus callosum is contained ui its original matrix or " com- missure-bed," which has become enormously but gradually elongated. This conclusion is strongly forced upon us by comparison, in the order mentioned, of such a series of 10* 66 DR. G. ELLIOT SMITH ON THE cerebra as those of the Iguana, Ornithorhynclnis^ Phascol- arctos, Perameles, Nyetophilus, Dasypus, and Talpa, with more highly-developed forms. In this process of forward extension the dorsal com- missure has carried forward its oAvn matrix, derived from the original " commissure-bed." It is obvious that if this takes place withovit a corresponding growth of the bridge of grey matter {s) which lies between the dorsal and ventral commissiu'es, we shall have pai't of the great longitudinal fissure (botmded on either side by the precommissural area) roofed in by the corpus callosum (contained, of course, in its proper matrix). This roofed space will be bounded posteriorly by the ventral limb of the " commissura dorsalis." This enclosed part of the great longitudinal fissure is the so- called "fifth ventricle^'' or " cavitm septi pellucUli." By means of the accompanying five schemes (in which the commissure-bed is shaded) T have graphically represented different stages in this process. From these schemes it will be readily recognized how the backward extension of the dorsal commissure (fig. 8) stretches not only the matrix in which it lies but also the sheet of the " precommissiiral body " {p.a.) which fills up the large angle between the two limbs of this commissure. Thus a portion of the pre- commissural body of each hemisphere becomes one of the leaves of the septum pellucidura. In liis valuable memoir Paul Martin speaks of a fusion taking place (in the brain of the cat) between the opposed walls of the hemisphere on the ventral side of the corpus callosum. In tliis manner, in the more highly-developed macrosmatic Eutherian cerebra, the massive corpora praecommissuralia below the corpus callosum may meet and fuse in the median plane so as to obliterate the cavum septi. But the commissure itself is not situated in anv such secondary fusion of the hemisphere walls, so that it does not aff'ect the main argument advanced above. But though the coi-pus praecomraissui'ale thus takes an important share in the formation of the septum pellucidum, part of it always remains distinct in the higher mammalian cerebrum as a vertical band, lying parallel to the lamina terminalis and separating the latter from the general pallium. This band is the "gyrus subcallosus " of Zuckerkandl. In order to show the last stage which this process reaches, I have represented in PI. 16. fig. 18 this region of the cerebmm /="/c. -?- Fie. 5. nc.e. Fic. 7. F'<^ Figs. 4-8. — Schemes to explain the evolution of the " septum pellu- cidum." Fig. 4 is a type of a Reptile. „ 5 ,, „ Monotreme. „ 6 „ „ Marsupial. OEIGIN OF THE COEPUS CALLOSUM. 67 of an adult man. The anterior extremity of the corpus callosum has become so bent that its rostrum (r.) becomes continuous with the remains of the " commissure- bed," which still surrounds the ventral commissure (c.v.). In this way the septum pcUucidum {sept.) becomes surrounded by a complete ring of the matrix of the commissiu-es and cut off from the gyrus subcallosus, which is the remainder of the precommissural area. This gyrus subcallosus extends down to the base of the cerebrum immediately in front of the ventral commissure and lamina cinerea {I.e.). Its line of separation from the pallium is indicated in the figure by a dotted line {a.l.). The gyrus subcallosus is traversed by a well-marked vertical depression — the Jissm-a jirima {fiss.])!'.), — Avhich has no important morphological significance. With the knowledge which we have acquired of the process of phylogenetic development of the region of the commissures, it is extremely instructive to study the beautiful figures with which Marchand, in man, and Paul Martin, in the cat, represent {op. cit.) the process of ontogenetic development. In the Marsupial we have a fissura arciiata or hippocampi, extending from the tip of the temporal pole right round the mesial wall of the hemisphere towards the olfactory pedimcle ; so, in the foetal child or kitten, we find the Bogenf urche (wliich we might, with Mihalkovics, appropriately call " Ammonsfurche ") following a similar course and shading away towards the cephalic pole of the hemisphere. And it is necessary to remark, in passing, that the so-called part of the " vordere Bogenfurche," which His calls " fissui'a j)rima," has noticing whatever to do with the true Bogenfurche or fissura arcuata, if we regard the latter as the primitive fissura hippocampi. In the early stages of the cat, the lamina terminalis becomes thickened and invaded by the commissural fibres of the fornix (Paul Martin), so in phylogcny we have the corresponding stages in the adult Monotremes and Marsupials. Then, as the commissural fibres increase in number, the grey mass or thickening of the lamina terminalis is invaded by so many white fibres that the grey substance seems to disappear, but it is in reality being gradually extended by the swelling commissure. The backwardly-extending commissure produces exactly the same series of changes — the same hippocampal flexure — in our phylogenetic series as it does in the developing brain of the cat and man (see Martin and Marchand's figures). Thus, for oil the stages in the developing brain of the cat, we can find almost exact prototypes among the more lowly-developed mammals. The great feature which far more than any other distinguishes the mammalian brain from that of all submammalia is the possession of a definite pallium — -distinct alike in its histological features and its morphological relations — giving rise to a definite internal capsule of projection-fibres and well-defined and fully-medvillated commissural fibres. At first, in the Monotremata and Marsuj)ialia, this pallium (like the parent mass of the basal ganglion from which it ajipears to have sprung) is united to its homologue of the opposite hemisphere by means of the " commissura ventralis " — " the commissure of the cerebral hemisphere " par excellence. But the rapid growth in extent and complexity of this general cortex or pallium is accompanied by a richer and more abundant commissural system. This growing commissural system from the dorsal part of the enormous pallium not only finds in the 68 DK. a. ELLIOT SMITH ON THE " commissura clorsalis " a shorter path, but a clearer scope for longitudinal extension than the ventral commissure provides. And tlms we have pallial fibres invading and subsequently superseding the dorsal limb of what was previously the hippocampal commissure. " Pallial " commissural fibres probably first make their appearance in Eeirtiles and form a very insignificant constituent of the ventral commissure. In Monotremes and Marsupials these fibres become extremely abundant, and swell the proportions of the ventral commissure enormously. But in Eutheria a rapidly increasing proportion of these fibres forsake the commissura ventralis and form the new " dorsal commissure of the pallium " — the corpus callosum, — which throws the " parent " commissure into insignificance. The remnant of the commissura ventralis is known in man by the somewhat misleading name " anterior commissure." EXPLANATION OE PLATES 15 & 16. Fig. 1. Coronal section througli the forebrain of Peranicles nasuta. Stained by Weigert's method. X4. The section passes just behind the commissures. 2. Coronal section through the hippocampal formation and the posterior extremity of the " com- missura dorsalis^' in Peramehs. Wcigert stain. Fascia dentata represented as it appears after nuclear staining, x 20. Figs. 3 & 5. Coronal sections of the " commissura dorsalis " of Perameles, a short distance in front of fig. 2. X about fi. Fig. 4. Representation of the commissures of Pernmek's (as seen in a mesial sagittal section) to show the planes in which the sections represented in figs. 2 («), 3 {b), 5 (c), and 6 (d) w-erc cut. 6. A coronal section of the cerebral hemispheres of Peram,eles, to show the general arrangement of the commissures. Wcigert stain, x about 6. 7. Coronal section of the right cerebral hemisphere of Perameles immediately in front of the cerebral commissures. Weigert-Pal and carmine stains, x 4. 8. Semi-schematic representation of the anterior part of the mesial wall of the cerebral hemisphere of Dasyurus vivervimis. X about 4. To show that, as a result of the unrolling of the hippo- campus anteriorly, the whole of its morpholoyicully superficial layer now actually forms part of the visible surface. Thus the surface of the hippocampus proper [hip.'") appears above the fascia dentata [f.d.'). 9. Anterior portion of the forebrain of Perameles, exposed in a mesial sagittal section. x 4^. The bulbus olfactorius only represented in part and in outline. 10. Sagittal section through part of the anterior portion of the mesial wall of the cerebral hemisphere of Phascolarctos cinereus. Weigert stain. X G. 11. Horizontal section through the left hemisphere of T/'icAosf^n/s ?;M/yje'c«/«, a short distance above the commissures, x 2. ant.mcs., the antero-mesial angle. 12. Coronal section through the right hippocampal formation of a bat [Miniopterus Schreibersii) , to compare with tlie hippocampal region of fig. 1. Lithinm-carniine stain. x about 20. 13. Coronal section o? Mi/iiopterus. Compare fig. 2. 14. Coronal section of right hemisphere of Miniopterus. X about 20. Compare with fig. 6. 15. The fascia dentata and adjacent parts. Enlarged from fig. 14. 16. Coronal section of the liippocampal region of Miniopterus, a short distance in front of fig. 14. 17. Sagittal section of the commissiires and adjacent parts of brain of Nyctophilus near the mesial plane. X about 40. 18. Drawing of the " gyrus subcallosus " of a human bram. OEIGIN OF T]IE COEPUS CALLOSUM. 69 ExplaHation of reference-lettei The significance of tlic reference-letters a, h, c, d, a, ^, y, a. I. Anterior limit of the " gyrus subcallosus.''' /. ali\ Alveus hippocampi. ciny. Cingulum. I.e. ciny' . Longitudinalfibresin the alveus hipjjocanipi l.v. adjacent to the cingulum. n.a. C.I). " Commissura dorsalis." n.c. CD.' Dorsal limb of the " commissura dorsalis." n.f.d. c.d". Ventral limb of the iMetatherian type of n.l. " commissura dorsalis." o.b. c.e. Capsula externa. o/;/. c.f. Columna fornicis. o.tr. c.i. Capsula interna. p. cm. Commissura mollis. p.a. c.r. Corona radiata. est. Corpus striatum. PJ/-f- c.v. " Commissura ventralis." pyr. d.f. Uesceudiug hippocampal or fornix-fibres. e. Epithelial fold roofing the third ventricle. r.o. e.o.t. External olfactory tract. s. f.d. Fascia deutata. sept. f.h. Fissura hippocampi. s.^r. fi. Fimbria. s.l. fi. The remains of the fimbria intermingled s.m.t. with fibres of the commissura dorsalis. spl. fix. The " subsplenial hippocampal flexure." s.r. f.r. Fissura rhinalis. s.t. g.h. Ganglion habenulte (and stria meduUaris s.t'. thalami). hip. Hippocampus. s.t". hip' . " Supracommissural hippocampus." sub. hip". "Precommissural hippocampus." t. hip'". Stratum zonale of the " precommissural hippocampus" lying upon the surface im- t.o. mediately above the stratum zonale [vd v. 3. molecularej of the fascia dentata [f.d.'). x. i. " Indusium vermn." i.l.s. Internal limiting sulcus of the tuberculum y. olfactorium {t.o.). •s in tlie Jigitfcs. h is explained in the text. " Longitudinal association bundles " of the hi[i2i{icampus. Lamina cinerca. Lateral ventricle. Nucleus amygdalae. Nucleus caudatus. Nucleus fasciae dentatae. Nucleus lenticularis. Olfactorj' bulb. Optic nerve. Optic tract. General cortex or pallium. "Precommissural area" or "corpus prm- commissurale." Pyriform lobe. Layer of pyramidal cells of the hippo- campus. Recessus ojiticus. " Commissure-bed." " Septum pellucidum." Stratum granulosum of the fascia dentata. Stratitm lacunosum of the hippocampus. Stria medullaris thalami. Splenium of the corjjus callosum. Stratum radiatum of the hippocampus. Stria terminalis. The crossing fibres of the stria terminalis entering the " commissura ventralis." The uncrossed part of the stria terminalis. Subiculum cornu ammonis. "Temporal pole" of the cerebral hemi- sjjhcre. Tiiberculum olfactorium . Third ventricle. MeduUated nerve-fibres stratum lacunosum. " Tract us hippocampi ad pallium." going to the Elliot Smith Trans Linn Soc Zool See 2,Yol.V1I,Pl 15 e.o I. rHiitK.Lith'Edin' HIPPOCAMPAL REGION OF BRAIN IN PERAMELES AND DASYURUS. Elhol Smith Trans Linn Soc Zool Ser 2,Vol VII.Pl 15 FHuth,Lilh'Edii!' HIPPOCAMPAL REGION OF BRAIN IN MARSUPIALS AND CHEIROPTERA. LINNEAN SOCIETY OF LOiNDON. MEMORANDA CONCERNING TRANSACTIONS. 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Part III. 1897. 8 1 4 1 8 16 12 5 1 7 12 6 12 8 12 18 2 8 6 4 8 6 2 1 11 10 1 4 10 8 12 2 6 (I 10 12 6 4 6 18 1 1 12 9 3 9 1 9 4 6 9 4 6 6 9 1 1 2 1 10 13 3 7 6 18 7 6 9 2 7 6 9 4 6 2nd Ser. ZOOLOGY.] [VOL. VII. PART 4. AUG 17 1893 THE io^lL TRANSACTIONS OF THE LINNEAN SOCIETY OE LONDON. ON THE MUSCULAR ATTACHMENT OF THE ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA (AMMONOIDEA). BY GEORGE CHAELES CRICK, F.G.S., F.Z.S., OF THE BRITISH MUSEUM (NATURAL HISTORY). {Communicated by the President, Dr. A. Gunther, M.A., F.R.S.) LONDON: PRINTED FOR THE LINNEAN SOCIETY BV TAYLOR AND FRANCIS. RKI) LION COURT, FLEET STREET. SOLD AT THE SOCIETY'S APARTMENTS, BURLINGTON-HOnSE, PICCADILLY, W. AND BY LONGMANS, GREEN, AND CO., PATERNOSTER-ROW. ^ June 1898. AUG 17 1893 r 71 IV. On the Mnscnlar Attachment of the Animal to its Shell in some Fossil Cephalo])oda [Ammonoidea). By G. C. CmcK, F.G.S., F.Z.S., of the British Iliiseum [Natural Sistory). [Communicated l»j the Piiesident.) (Plates 17-20.) Read 3rfl February, 1S!)8. INDIC^ITIONS of the muscular attachment of the animal to its shell have been tigured in not a few Nautiloids, but comparatively few Ammonoids have been recorded in which what has been believed to be the remains of this attachment has been iigured and described. Of these the best known are Oppel's figures of three examples of Ammonites steraspis* from the Lithographic Stone of Bavaria, iiublished in 1863, in which the body-chamber of each is shown to be traversed by a fine curved line, the relation of which to the animal was not, however, indicated by the author. In 1870, Trautschold f figured a specimen of Ammonites hicurnatus, exhibiting what he considered to be the impression of the muscular attachment of the animal, but this figure differs considerably from Oppel's figiu'cs. In the following year, Dr. W. Waagen % published his important paper, " Ueber die Ansatzstelle der Haftmuskeln beim Nautilus und Ammonoiden," in which he expressed his opinion that the " shell-muscle " in the Ammonoidea was attached to the inner (umbilical) portion of the lateral area of the whorl. He believed the curved line figured by Oppel on the body-chamber of Ammonites steraspis to be a trace of the " annulus," and probably also of the shell-muscle, and, reproducing one of Oppel's figures, he completed by a dotted line what he considered to be the form of the shell- muscle. This interpretation of Oppel's figures has been accepted by most authors. In 1879, Eck § figured and described a small septate fragment of Ceratites semipartitus from the Upper Muschelkalk of Schwielierdingen, near Stvittgart, Avhich he thought showed not only the appearance of the surface of the mantle (the so-called " epidermids "), but also the impression of the annulus. The specimen was merely an internal cast of five chambers, and on the surface of the cast of each chamber there was a depressed zone with a finely-pitted surface, occupying on the siphonal region the middle two-thirds, and becoming much narrower on the side of the whorl ; in two of the chambers a groove was also present on the antisiphonal area. * Pal. Mittheil. p. :2.j1, pi. Ixis. figs. 1, 2, & 6 (1863). t Bull. Soc. Nat. Moscou, vol. xliii. pp. 301-306 (1870). t Pateontographica, vol. xvii. pp. 185-210, pis. xxsis. & xl. (1871). § Zeitschr. deutsch. geol. Gesell. vol. xxxi. p. 276, pi. iv. figs. 5 a-d (1879). SECOND SERIES. — ZOOLOGY, VOL. VII. 11 72 MR. G. C. CRICK OX THE MUSCULAR ATTACHMENT OF THE In his lai'ge works on the Triassic Cephalopoda, Dr. E. von Mojsisovics * has figured several species of Ammouoids bearing on the internal cast of their body-chamber a groove or grooves (extending in some examples from the umbilicus on one side, over the peripliery, to tbe umbilicus on the other side), vrhicli he considered to be the impression of the homologue of tiie muscular attachment of the recent Nautilus. Dr. O. Jaekel t, in 1889, figured a Ceratite from the Trias of Riidersdorf, near Berlin, bearing a groove precisely similar to those figured by Dr. E. vou Mojsisovics, and although he douljted this indicating the position of the homologue of the annukis and of the shell-muscle in the recent Nautilus, he was unable to give any explanation of its nature. After an examination of Oppel's original specimen, this author says the line which Oppel figured and which has been regarded as indicating the position of the anterior boundary of the anuulus and of the shell-muscle can scarcely be folloAved with certainty, and he is inclined to doubt tiie correctness of the interpretation. In his ' Vorlaufige Mittheilung liber die Organisation der Ammoniteu ' +, Dr. Stein- mann evidently does not agree with Dr. Waagen's interpretation of Oppel's specimens (although he seems to make no special reference to them), a fact which is clearly brought out in the ' Elemente der Palaontologie ' (1890) by himself and Doderlein, where (p. 351, fig. 402) one of Oppel's figures (Pal. Mittheil. pi. Ixix. fig. 2) is reproduced, and tbe curved line on the body-clianiber completed in the manner suggested by Waagen, but in the explanation of the figure this line is thus described : " (?) vordere Greuze des Haftbandes." At the meeting of the Geological Society of London which was held on March 25th, 1891, a communication was read from Mr. S. S. Buckman, entitled " Notes on Nautili and Ammonites." Only an abstract of the paper was published §. Nautili and Ammonites were exhibited in illustration of the paper, and, according to the abstract, " Two specimens exhibited show long spatulate depressions more or less parallel to the periphery for about half the length of the body-chamber. It was suggested that these impressions indicated the position of the shell-muscles." So far, then, as I have been able to ascertain, no satisfactory examples exhibiting the form and position of the musctdar attachment of the Ammonoid animal to its shell have yet been figured and described either to confirm or to contradict the explanation whicli AVaageu gave of Oppel's figures. The Ammonite animal may have been, and prol)ably a\ as, attached to its shell at the edge of the last septum, as in the living Nautilus, but from my own observations it is * Abhaudl. d. k.-k. geol. Eeichsanst. Wieii, Bd. vi. Theil i. Heft i. (1873) pi. xvi. f. 3 {Phi/lloceras occidfum) ; pi. xix. f. 1 (Pinucoceras transiens) ; pi. xix. ff. '2, 3, 4 & pi. xx. ff . 8 &: 9 {Pmacoceras Jiumile) ; pi. xx. ff. 2, 3, 5, & 7 (Pivxicoceras insectum) ; [il. xxii. ff. 7, 8 {Pi nacoceras mi/ophorum) ; ibid. Bd. vi. Hiilf'te ii. (1893) pi. cxxxiv. f. 1 {Choristocei'fis amiiwnh'ifornu); ihUl. Bd. x. (1882) pi. liii. f. 2 (Mec/aj}hi/lKtes sandalinus); pi. liii. f. ;5 {Mega- phyllites oholus). t " Ueber eineu Ceratiteu aus dem Schaumkalk vou lliider.sdorf uud iiber gewisse als Haftring godeutete Eindriicke bei Cephalopoden," Ncues Jahrb. 18S9, ii. p. 19, pl.i. + Berichtc der naturforsehendcu Gesellschaft zu Freiburg, Bd. iv. Heft 3, jip. 31-47 (1889). § Abstr. Proc. Geol. Soc. Loudou, Session 1890-91, p. 105 (Quart. Journ. Geol. Soc. vol. xlvii.). ANIMAL TO ITS SHELL IN SOME POSSIL CEPHALOPODA. 73 quite clear that it was furnished with shell-muscles and an annulus like the recent Nautilus, and it is the object of the present communication to record the indications of these structures in various Ammonoids. It is not proposed here to record every Amnionoid in which these imj)ressions have been observed — this I hope to be able to do subsequently — but to describe the form and position of these impressions so far as I have been able to observe them in the different forms which the Ammonoids assume, e.g. in BacnUtes, Hamitcs, Crloceras, Ancylooeras, Macroscapliites, Scaphites, and Tiirr/lHes, the group of the Ammonites (ranging from very evolute to almost entirely involute forms), as Avell as in Chjmenia and the group of the Goniatites. It may be well at the outset to refer to the indications of the shell-muscles and of the annulus as they exist in the shell of tlie recent Nautilus, and for this purpose it will probably suffice among the many figures which have been published of the m.uscular attachment of the I'ecent Nautilus to call attention to the figures accompanying Dr. Waagen's paper already alluded to (p. 71)*. I may, however, here remark that in the recent Nautilus the shell-muscles are ear-shaped and situated upon each side of the animal ; they are connected both on the dorsal and on the ventral side by a narrow band — the annulus. The shell-muscles are not inserted into the shell-substance, but are merely applied to the innei* surface of the test with the intervention of a thin layer of conchiolin ; and all that is usually preserved in the interior of the shell to indicate the form and position of the muscular attachment is a fine, generalh' raised line, corre- sponding to the anterior boundary of the annulus and of each shell-muscle; it is only rarely that there are any indications of the posterior boundary of these structures. On an internal cast this raised line would be represented by an incised line, and since in fossils the remains of the muscular attachment are preserved almost always on internal casts, they therefore exist as incised lines. Such structures have been described and figured in not a few fossil Nautiloids, including the genus Nantilns itself. In the fossil forms any recoi'd of the form and jiosition of the muscular attachment would, when present, usually be preserved iipon the surface of the natural internal cast of the body- chamber, and hence raised lines on the inner surface of the original test would appear on the internal cast as incised lines, and clce versa. In order to observe in the recent Nautilus the exact position of the muscular attach- ment with relation to the edge of the last septum, an artificial cast of the shell ot Ndiitilvs pompilius w^as made by filling a sagittal section of a recent shell with paraffin wax, and then dissolving aw'ay the shelly matrix with hydrochloric acid. The anterior boundary of the muscular attachment alone was indicated by a very finely incised line. To show the usual position of the muscular attachment in Ammonoids, and for the better understanding of the less perfectly preserved examples, it is proposed first to describe the impressions of the " muscular scars " in the specimen on which they have been most clearly seen, and then the specimen in which the remains of the annulus have been most clearly observed. The former is an example of Crloceras from the * See also the receiitlj'-published paper by L. E. Griffin, " Notes on the Anatomy of N(n(tilu.s pomjnlncs," Zoo]. Bull. vol. i. no. 3, pp. 147-161 ; with bibliography. 11* 74 MR. G. C. CKICK ON THE MUSCULAR ATTACHMENT OF THE Speeton Clay, and the latter an Oxfordian Ammonite, now referred to the genus Cardioceras. Then it is proposed to descrihe the form and position of the scars and of the annulus (when seen) in various forms of Ammonoids, ranging from the straight (in the adult) from Bacidites, through Uamites, Crioceras, Ancyloceras, IlacroscapMtes^ Scaphites, and Tnrril'des to the group of the Ammonites ; then in Clymenia and the group of the Goniatites. The A^ery fragmentary character, and consequently imperfect determination, of some of the specimens must he mentioned; hut, hearing in mind the position of the shell- muscles in the Ammonoid, viz. on the inner portion of the whorl, it will he at once evident that the traces of the muscular attachment are more likely to he found in fragmentary specimens, principally on natural internal casts of the body-chamber. Muscular Scars. Tlie muscular scars have been best observed in a fragment of Crioceras qnadratnm *, n. sp., which I obtained from the Speeton Clay of Yorkshire (PL 17. figs. 10, 11). It consists merely of the base of the body-chamber, and is about 38 mm. long. The greater part of the test, which was in a very soft, white, friable condition, has been removed by a stiff brush, so as to expose the surface of the internal cast of the body-chamber without scratching it. The section of the whorl is subquadrate, the outer area being somewhat narrower than the inner ; at the last septum the height of the whorl is 29 mm., and its greatest thickness 27 mm. On the inner (dorsal) area of the internal cast, and near the posterior extremity of the body-chamber, there are two oval areas, one on either side of the median line, the major and transverse diameters of etich being 14 mm. and 11 mm. respectively. The longer diameter of each is placed transversely, but not quite at right angles to the median line, the inner end of this diameter being slightly in advance of the outer extremity. The two impressions ai*e nearly in contact, being only about 05 mm. apart at the inner or anterior end of their respective longer diameters ; their posterior borders are only slightly in advance of the last septum. Each impression is very slightly roughened, and consequently distinct from the surrounding and somewhat polished siu'face of the cast. An incised line forms its boundary on the inner, antei'ior, md outer sides, being deepest on the anterior side, while its posterior boundary is marked by a faint, somewhat irregular and imperfectly-defined line. No trace of the portion of the annulus surroimding the base of the body-chamber, and connecting the muscular impression on the one side Avith the muscular impression on the other side, can be seen. In the triangular space between the two impressions, and 3 mm. posterior to the point where they are nearest together, there is near each incised line a veiy small, shallow, double pit, each pair of pits being disposed longitudinally ; these doubtless were connected with the muscular attachment of the animal to its shell. * This is really a Bean MS. name. Some of the examples of this species in the British Museum Collection bear this name in Bean's handwriting, and I have adopted tlic name, since, so tar as I know, the species has not j'et lieen described. ANIMAL TO ITS .SHELL IN SOME FOSSIL CEPHALOPODA. 75 Animlus. The impression of the annuius lias been observed in several specimeDS, but in the British Museum Collection (No. C. 6801) there is an example of Cardioceras excavatimi (J. Sowerby) * from the Oxford Clay, but the locality is not recorded, in whicli the form of the miiscular attachment, and particularly that of the annuius, is remarkably well displayed (PI. 18. fig. 8). The specimen is apparently complete, and shows the aperture of the shell, which is provided with a narrow, ventral (or peripheral) apophysis. Its dimensions are : — Diameter of shell 120 mm. ; width of umbilicus 21 mm. ; height of outer whorl 58 mm. ; ditto above preceding- whorl 40 mm. ; thickness of outer whorl about 43 mm. The body-chamber occupies the last half of the outer whorl, its base being 44 mm. high and 29 mm. wide or thick. The whorl is subsagittate in transverse section ; its inner margin slightly overhangs the umbilicus, so that the width of the umbilicus, measured at the umbilical margin, is less than that measured at the suture of the shell. A greater part of the test is preserved, and this is mostly in a soft friable condition. Some of it had been removed from the left t side of the specimen, so as to expose a portion of the internal cast of the base of the body-chamber. By means of a small stiff brush the rest of the test was carefully cleared from both sides of the base of the body-chamber, and the form of the muscular attachment of the animal was displayed very clearly, especially on the left side, the attachment on the right side being jjreciselv similar, but a little less distinct. On the left side the impression of the anterior boundary of the shell-muscle crosses the umbilical margin 5 mm. in advance of the last septum, and passes as a very narrow l)and of a. thin film backward and outward in a flat forwardly- convex curve as far as the middle of the second lateral lobe, at which point, and 1"5 mm. posterior to it, there is seen to be another similar band Avhich passes from the mnbilicus immediately above the saddle on the margin of the umbilicus ; these two bands, con- tinuing at abou.t the same distance apart, pass over the lateral saddle into the first lateral lobe and, then diverging slightly, pass over the peripheral or external saddle forward and outward towards the jjeriphery in a flat forwardly-convex curve, but becoming very indistinct before reaching the periphery. These two very narrow filmy bands appear to l3e the remains of the anterior and posterior boundaries of the annuius respectively. Remains of the annuius are visible also on the right side, but much less distinctly ; they are, however, sufficiently clear to confirm the structures which have been mentioned as existing on the left side. Having described the usual form of the muscular scars and of the annuhis, I now proceed to describe their remains in various forms of Ammonoids, commencino" with the genus Bactilites and proceeding in the order already indicated {ante, p. 73). * J. Sowerby, Min. Con. voL ii. p. 5, pL cv. (1815). t The terms " right " and " left " are used in a strictly morphological sense, the periphery (or siphoual area) of au Amnionoid being ventral, and the anti])eripheral (or autisiphonal) area dorsal. 76 MR. G. C. CRICK ON THE MUSCULAR ATTACHMENT OF THE Order of Descriptions. Page Baciilifes, Lamarck 77 Samites, Parkinson 79 Crioceras, Leveillo 79 Aiicyloceras, d'Orbigny 80 Macroscaphifes, Meek 81 Scaphites, Parkiuson 81 Turrilites, Lamarck 83 [Metcroccras, d'Orbigny) 84 AMMONPrES 85 AmaltheidtE, Pischer 86 Oxi/)wticeras, Hyatt 85 Amalthens, Montfort 86 Cardioeeras, Neumayr & Uhlig 86 Neumayria, Nikitin 89 Tissotia, Douville 90 Lytoceratid^e, Neumayr, emend. Zittel. Lytoceras, Suess 91 -Sgocekatid^, Neumayr, emend. Zittel. Arietites, "Waagen 93 ^goceras, Waagen, emend. Zittel 95 Sonninia, Bayle 98 Harpoceratid^, Neumayr, emend. Zittel. Secticoeeras, Bonarelli 98 (Ecotranstes, Waagen 99 DisticJioceras, Munier-Chalmas 100 Stephanoceratidje, Neumayr, emend. Zittel. Stephanoceras, Waagen 101 Pei'isphi notes, Waagen 102 Aspidoceratid-E, Zittel. T?eltoceras, Waagen 102 Aspidoceras, Zittel 103 CoSMOCERATIDiE, Zittel. I'arkinsonia, Bayle 103 Prionotropip.e, Zittel. Schlcenbachia, Neumayr 104 Clymenia, Miinster . 105 GONIATITES. Glyphioceras, Hyatt .... 106 ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHjVLOPODA. 77 Baculites, Lamarck. Baculites ovatus, Say. — An example of this species in the British Museum (No. C. 5415 f/) from the Fox Hill beds (Upper Cretaceous) of Horse-head Creek, South Dakota, U.S.A., displays the impression of the shell-muscles very clearly. The specimen consists of the natural cast of nearly the whole of the body-chamber, the cast of the last locvilus and of a portion of the penultimate loculus. The test has been almost entii'ely removed from the posterior part of the body-chamber (PI. 17. figs. 1, 2, ifc 3). The shell in this species is laterally compressed, and tapers very slowly. The length of the specimen is 290 mm. or abont 11^ inches ; its transverse section is oval, the greatest thickness being a little nearer the antisiphonal (dorsal) than the siphonal (ventral) area. Of this length the body-chamber occupies 215 mm., but the aperture is not preserved. The ventro-dorsal and transverse diameters of the base are 38 and 25'5 mm. respectively. The two muscular impressions are at the base of the body-chamber and on the antisij)honal (dorsal) area ; the inner, antei'ior, and outer portions of their botmdaries can be distinctly traced as a faint, shallow, depressed (not sharply-incised) line. On the antisiphonal area the suture-line has a small antisiphonal lobe separating the two portions of a broad saddle, each portion corresponding to the second lateral saddle in an ammonite ; each of these halves is followed by a rather broad lobe (the second lateral) which separates it from the saddle occupying nearly the middle of the lateral area, L e. the first lateral saddle. The median line of the antisiphonal area is occupied by a very shallow longitu- dinal groove. The inner boundaries of the two muscvilar impressions seem to meet in the middle line at about 2'5 mm. in advance of the most anterior part of the saddle, adjoining the antisiphonal lobe. Starting from this point, the boundary of the impression passes forward and outward until it is S"5 mm. from the same j)art of the suture-line ; then, turning backward and still maintaining its course outward, it passes along the outer side of the second lateral lobe, close to the inner side of the first lateral saddle. The boundary of the other impression has a precisely similar course. The impressions are somewhat oval, their longer diameters making an angle of about 45 with the median line of the antisiphonal (or dorsal) area. At a point slightly below the level of the most anterior part of the adjoining saddle (the first lateral) the outer boundary of each impi'cssion is a little angular. On one (the right) side of the specimen no trace of the annulus can be seen, but on the other (the left) side a line is seen to pass from the angular portion of the impression outward and upw'ard over, and about 1 mm. distant from, the adjoining saddle ; although it can be traced only for a short distance, owing to the roughness of the siuface here, it doubtless represents the anterior boundary of a portion of the annulus. At a distance of 5 mm. in front of the boundary of the impression on the right side, there is another line having precisely the same curvature. It is not nearly so distinct as the one just described, but most probably indicates the anterior boundary of the same shell-muscle. Possibly the posterior line denotes the position of the shell-muscle diu'ing the formation of a septum, and therefore dui'ing a period of rest, when the muscle would 78 ME. G. C. CRICK ON THE MUSCULAE ATTACHMENT OF THE become firmly attached to the shell. The anterior faintly-impressed line may have been the last attachment of the anterior boundary of the shell-muscle during the gradual growth of the animal upward prior to the formation of a new septum. The corresponding line on the left side is obscured by the shelly matter adhering to the cast. On the median portion of the peripheral area the septum j^ossesses a rather broad (median) saddle, on either side of which is a small lobe — the two halves of the peripheral lobe. This is followed by the peripheral or external saddle. Anterior to the septum and on the central portion of the same area there is a feebly -incised line having the form of half an ellipse (PL 17. fig. 3) ; it arises close to the outer portion of the external (or peripheral) saddle, i. e. at about 7 mm. from the median line of the siphonal (ventral) area ; then curves upward and towards the median line, attaining its greatest height at about 8'5 mm. in front of the median saddle, or about 5'5 mm. from its commencement. The line seems then to pass on to the other side without interruption, but the surface of the cast is not sufiici- ently well preserved to enable this to be stated w4th certainty. Its anterior portion is about on the same level as the anterior portion of the boundary of the muscular impression. About 6 mm. in front of this curve there is a similarly-curved feebly-impressed line, w'hich inost probably is comparable with the faint curve on the opposite (antisiphonal) surface. Although the annulus is not well shown in this example, there is another specimen [C. 5415 Jj] in the British Museum, from the same horizon and locality (PI. 17. fig. 4), which displays the muscular impression less distinctly, but clearly shows the anterior boundary of a portion of the annulus. This leaves the muscular impression at the " angle " mentioned in the previous description, and, passing upward over the adjoining saddle at a distance of about 1*5 mm. from the siiture-line, crosses the next lobe in a shallow depression, arid again rises over the next saddle iit about the same distance from it as before. This depression, however, is seen only with difficulty and by turning the specimen about in a fairly good light. There can, I think, be no doubt that the annulus was in the form of a simply-w^aved band, being elevated at the saddles and very feebly depressed in each lobe just as in the example of Cardioceras excavatum already described (p. 75). The total length of the specimen is 245 mm., the body-chamber (the aperture of which is not preserved) occupying 165 mm., the diameters of the base of tlie body-chamber being 44 and 31"5 mm. respectively. The other side of the cast of the body-chamber is obscured by fragments of the test. BacHlites vagina , Porbes. — A portion of the muscular impression has also been seen in an example of this species in the British Museimi Collection [one of the specimens numbered 83624] from the Upper Cretaceous of Pondicherry, India (PI. 17. fig. 5). It is merely the internal cast of the greater portion of the body-chamber, about 60 mm. long, anteriorly incomplete, but fairly perfect posteriorly. Its transverse section is oval, the diameters of its antei-ior end being 24 and 145 mm. ; those of the posterior end being 19 and 12-5 mm. The antisiphonal surface is broad and slightly flattened, the siphonal being narrow, flattened, and with suliangular borders. On the broad antisiphonal svu-face the feebly convex boundaries of the two muscular scars (indicated by a feebly-incised line ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 79 on the internal cast) meet nearly in the middle line in an obtuse backwardly-directed point whicli is 3*25 mm. in advance of the saddle on either side of the antisiplional lobe, these two saddles occupying a large portion of the autisiphonal area. From this point each Ijoundary passes forward and outward for a short distance, then turns backward and sweeps over on to the lateral area in a broad anterioi'ly-convex curve whicli gradually disajipears before reaching the last septum ; if continued to the septum it would meet the large lateral lobe on its antisiphonal side. It would seem tlierefore that, just as in the Baculites already described, the muscular scar on either side occupied the space between the central line of tiie autisiphonal area and the antisiphonal side of the large lateral saddle. There is no trace of the annulus in this example. Hamites, Parkinson. Samites viaximus, J. Sowerby *. — In the British Museum Collection (No. C. 6S02) there is an example of this species, from the Gault of Folkestone, which displays the form of the muscular scars exceedingly well (PI. 17. figs. 0, 7). It is only a fragment, /. e. one portion (the larger) of the terminal hook, and consists of the internal cast of the last loculus and of a portion of the body-chamber ; its length, measured on the pcrij)hery, is about 55 mm. The whorl is subcircular in section, only slightly compressed, its ventro-dorsal diameter (excluding the ribs) at the base of the body-chamber being 16 mm., and its transverse diameter (also excluding tlie riljs) 15 5 mm. Tlie impressions of the muscular scars are seen on the inner (dorsal) surface of the cast of the base of the body-chamber, one on either side of the median line and disposed souieAvhat oldiquely, just as in the exara2:>le of Crioceras quadraium already described in this paper {ante, p. 74). Each scar is elliptical in outline, and enclosed by a very faintly-incised line ; its longer axis is inclined to the median line of the dorsal surface of the body-chamber at an angle of about 45°; its posterior boundary is only about 1"5 mm. anterior to the antisiphonal saddle of the last septum. Anteriorly the impressions are 1 mm. apart. The longitudinal and trans- verse diameters of each scar are 12 and 10 mm. respectively. At about the middle of the outer portion of the boundary there is a slight angularity, which doubtless indicates the position of the commencement of tlie anterior border of the annulus, but no other traces of the annulus have been observed. In another example which is figured (PI. 17. tigs. 8, 9) each muscular scar bears a small roughened patch, and there are indications of a narrow band connecting the scars. Crioceiias, Leveille. Crioceras quadratumf, n. sp. — The muscular impressions in this genus have been best observed in two examples of Crioceras quadratam from the Speeton Clay, Yorkshire. One of these has already been described (see p. 74). The other forms part of the British Museum Collection (No. 89102). It consists of the natural cast of the body-chamber with * J. Sowerby, Min. Con. vol. i. p. 138, pi. lxii.(1814). t See footnote, ante, p. 74. SECOND SERIES. — ZOOLOGY, VOL. VII. 12 so ME. G. C. CEICK ON THE MUSCULAE ATTACHMENT OF THE only fragments of the test adliering to it. At the base of the body-chamber the whorl is subquadratein section, its height being 35 mm., and its greatest width 31 mm. (PI. 17. figs. 12, 13). The imi:)ressions are not so complete as in the example just described. The anterior margin of each is indicated by a sharply-incised line ; both lines almost meet each other in the median line of the inner (dorsal) area at about 10 mm. anterior to the summit of the innermost portion of the saddle on either side of the antisiphonal lobe. Dis- appearing posteriorly, each passes forward and outward for a length of about 10 mm., when each is about 5 mm. in advance of its origin ; then, turning abruptly backward, each gradually disappears at a distance of about 9 mm. from its point of origin and about 14 mm. from the median line. The posterior extremity of each has a tendency to turn outward, and at a short distance from the extremity the line gives off a very faint branch wdiich turns inward, but can be traced only for a short distance. Without doubt the faint line turning inward represents the boundary of the impression of the shell-muscle, and that continuing in an outward direction indicates the position of the anterior border of the adjacent portion of the annulus. Ancyloceeas, d'Orbigny. Ancyloceras Matheronimmm, d'Orbigny. — In the genus Aucyloccras what is be- lieved to be the impression of the mviscular attachment of the animal has been best seen in an example of Ancyloceras Matlieronimmm in the British Museum Collection (No. 0. 5322). It is a natural internal cast from the Neocomian of Cassis (Bouches-du- Pi,h6ne), France (PL 17. figs. 14, 15, 16). The coiled part of the septate portion is wanting, but the rest is fairly well preserved, although much waterworn. The body-chamber, measured along the centre of the periphery, is 380 mm. long ; the cross section of its base is oval, the dorsal (or inner) portion being somewhat wider than the ventral (or outer) ; the veutro-dorsal diameter (or height) of the base is 75 mm., the transverse diameter {i. e. the thickness) 54 mm. (excluding the tubercles). What I regard as the impressions of the boundaries of the two muscular scars are seen on the inner or dorsal area. The two scars are not quite symmetrical, that on the right side extending about 15 mm. further forwards than that on the left. These boundary-lines are incised, but they are much coarser than usual. This, however, is probably due to the -waterworn condition of the specimen, for the septal sutures, instead of being iinely -incised lines as usual, are fairly deep and wide, and indeed have quite the appearance of having been considerably water- worn ; and this condition of the septal sutures suppoi'ts the opinion that the lines about to be described are really the impressions of the boundaries of the muscular scars. That on the right commences at about 3 mm. to the right of the median line and about 20 mm. in front of the large saddle adjoining the antisiphonal lobe ; passing forward for about 35 mm. and approaching nearer the median line, it then turns outward, but still continues forward until at about 50 mm. from the last septum, when it turns still more outward and then disappears. That on the left appears to arise about 43 mm. in front of the miost anterior portion of the saddle adjoining the antisiphonal lobe, and about 6 mm. from the boundary on the right side ; passing forward and outward for nearly ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 81 20 mm., it is then at about 58 mm. from the last septum ; then with a broad curve it turns backward until it is about 40 mm. from its commencement, when it appears to rapidly die out. Although the impressions of these boundaries may perhaps be more properly termed grooves, their form and position agree so well with what I have observed in somewhat similar forms that I think there can be no doubt as to their nature. I have not been able to observe any trace of the annulus in this example. Mackoscaphites, Meek. Ifacroscophites fjigos, J. de C. Sowerby, sp. — In the genus Ilacroscaphites what 1 regard as the anterior boundary of the muscular scar has been observed in an example of Ilacroscaphites gigas, J. de C. Sowerby, sp., in the British Museum Collection (No. 32008). The specimen is stated to be from the Lower Greensand of the Isle of Wight, but its matrix and state of preservation suggest rather the Kentish Rag (Lower Greensand) in the neighbourhood of Maidstone (PI. 17. figs. 17, 18, 19). It is a much-compressed internal cast ; the greatest diameter of its sej)tate jjortion is 180 mm. ; the length of its body-chamber measured along the centre of the periphery and over the coarse ribs is 350 mm., the height of the base of the body-chamber is 68 mm., the thickness (including the ribs) being reduced by compression to 22'5 mm. On the right side, at about 15 mm. above the most anterior part of the last septum and 20 mm. irom the inner margin of the whorl when viewed laterally, a very fine incised line arises and passes thence as a flat arc forward and towards the inner margin, which it crosses at about 45 mm. in front of tlie last septum ; it then curves backward and comes to within about 10 mm. of the septum, w^here it is in the middle line of the compressed and somewhat distorted dorsal area. From this point another line, making an acute angle with the line just described, j)asses forward and outw^ard for rather more than 30 mm., when it curves outward still more and then disappears. These two curved lines we take to be the anterior boundary of the right and left muscular scars respectively ; no traces of the annulus have been observed in this example. The material of this natural internal cast is very coarse, and the specimen is so much crushed that the very faint lines bounding the muscular scars can only be followed with difficulty ; the boundary is preserved partly as an incised line and partly as a line of colour. ScAPHiTES, Parkinson. Scctphites biuodosus, A. Roemer. — The muscular impression can be traced in an example of this species contained in the British Museum Collection (No. C. 5182). It is from the Lower Senonian (Granulaten-Kreide) of Broitzen, near Brunswdck. The specimen is a fairly well-preserved, but somewhat distorted internal cast. Its greatest length is 43 mm., and the greatest diameter of the septate portion is 26-5 mm. (PI. 17. figs. 20, 21). At the posterior end of the body-chamber the whorl is 13'5 mm. higli and 10"5 mm. thick (excluding the tubercles). The whorl is somew'hat crushed obliquely, so that its sloping- inner area is much more clearly seen on one (the left) side. On this side a feebly-incised (partly double) line arises almost close to the last septum, and at a distance of 5 mm. 12* 82 MK. G. C. CRICK ON THE MUSCULAR ATTACHMENT OF THE from the inner edge of tlie Avliorl ; passing fovAvard in a broad, flattened, forwavdly- convex cui've, it graduall}^ approaches and finally crosses the inner edge of the whorl at about 7*5 mm. in front of the last septum. Passing on to the dorsal (or concave) portion of the whorl, it turns backward, and in a rather broad forwardly-convex curve nearly reaches the centre of this area, where it appears to be joined by the corresponding impression on the opposite side. The boundary of the impression on the opposite side is not quite so distinct, and on the sloping inner area of the whorl it appears to be a little nearer the inner edge of tlie whorl than on the opposite side, but this is doubtless due in great measure to the oblique crushing to which the specimen has been subjected. At the base of the body-chamber it is only 2-75 mm. from the inner edge of the whorl; passing forward it gradually approaches and finally crosses the same at about 7'5 mm. in advance of the last septum. I'assing thence in a forwardly-convex carve, it joins its fellow at about the centre of the dorsal surface of the whorl. The lines here described are probably the boundaries of the muscular scars. I have not seen any indications of the annulus in this specimen. ScapJdtes ceqiialis, J. Sowerby. — The muscular attachment of the animal has also been observed in an example of Scaphites (eqiialis, J. Sowerby, in the British Museum Collection (larger of the two specimens, No. S9113). The specimen is an exceedingly well-preserved and almost perfect natural internal cast from the Lower Chalk of Doi'set. The greatest length of the specimen is 21) mm. ; the greatest diameter of the sejjtate part (which is at the base of the body-chamber) is 15-5 mm., the whorl here being 9 mm. high and 11 mm. wide (excluding the tubercles). The mouth-border is well preserved. The anterior border of the muscular attachment is preserved on the lateral area as a very faint line arising (on the leit side) almost close to the last septum and at about 1'5 mm. from the edge of the whorl, and passing forward and towards the edge of the whorl crosses this edge somewhat obliquely at about G'5 mm. in advance of the last septum. Fortunately a portion of the body-chamber can be removed so that the course of this line can be satisfactorily traced. Continuing still forward it passes into a fairly wide shallow groove 4 mm. in front of the most anterior portion of the septate part of the shell, the groove being disposed across the floor or concave portion of the body-chamber in a flat forwardly-convex curve, with a very slight backward depression at the centre of the area. A similar fine line can be somewhat less distinctly traced on the right side of the specimen, passing into the same groove on the floor of the body-chamber. About 3 75 mm. posterior to the groove just mentioned there is another similar but narrower groove. From my examination of other specimens it is not unlikely that this will prove to be the posterior boundary of the shell-muscles, which seem to have been united on the concave portion of the body-chamber into a fairly wide band. The shell-muscles then appear to have been almost confined to the concave area of the body-chamber, only a narrow portion extending on to the lateral area. In the British Museum Collection (No. C. GSOO) there is also a fragmentary example of the same species (PI. 17. fig. 22), from the concave portion of the body-chamber of which the matrix has been removed as carefully as possible. There is a similar line on the lateral ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 83 area, passing into a shallow groove on tlie concave portion of the body-chamber, but the part of the latter between the groove and the anterior ini]n"essed line produced by the ornaments of the septate part of the shell is covered with a thin, yellowish, powdery layer, quite unlike the rest of the concave portion of the body-cbamber. This in all probability indicated tlie place of attachment of the shell-muscles. I bave not observed tlie remains of tbe annulus iji any example of this species that has come under my notice. TuKKiLiTES, Lamarck. Tm'7'ilites tuberculatus, Bosc. — An example of this species in tbe Museum of Practical Geology (No. 6372) from the Lower Chalk of Cliffe Anstey, Wilts, displays tbe anterior border of the muscular scars exceedingly Avell (PI. 18. ligs. 1, 2). Tbe specimen is a natural internal cast of about live Avliorls, the smallest of whicb is somewhat imperfect, and the rest fairly well preserved. Two of the upper wliorls show that the sipbuucle [si) is situated at about one-sixth of tbe height of the whorl below the suture of the shell. Unfortunately the suture-line is not well shown, so that it is not possible to say exactly where the body-chc^mber commences. Tbe aperture is fairly well preserved. The height of the last whorl (from the lowest of the three rows of small tubercles to tbe suture of tbe shell) is about 52 mm. ; the Avidth of the whorl (/. e. the distance across the specimen) being 1085 mm. Tbe anterior border of the muscubu- attachment is well shown on the last whorl as a well-marked narrow groove. VicAving the specimen with the aperture away from you and directed downward, tbe course of this groove may be thus described : — Commencing somewhat below the centre of the whorl it passes for a very short distance (about 2 mm.) downward and to the right ; then, turning still more to the right, it passes for a distance of about 13 mm. with a bold convex curve to within 12-5 mm. of the lowest row of smaller tubercles ; then turning again still more to the right it glasses under the uppermost row of small tubercles. Just beneath the tubercle to the left of the one under which this groove passes there are indications of a septal suture ; this is believed to be the last septum, and therefore to indicate the commencement of the body- chamber. Passing still to tbe light and down\Aard in a broad feebly-convex curve, and at the same time becoming deeper, the groove crosses the two lower rows of small tubercles at about 30 mm. from the last-mentioned bend ; it is continued on to the surface below the tubercles until at about 10 mm. below the lowest row it curves round in a broad curve and passes to the left for a short distance; then at about 21 mm. below the lowest row of tubercles it makes an angular bend, passes downward and to the left for a distance of 11 mm., when it curves upward and passes into the umbilicus ; this upward portion can be traced for about 2'1< mm., when it is obscured by matrix. With the exception of the 15 mm. first described, probably the whole of this incised line represents the anterior boundary of the two muscular scars. Turi'ilites Mantelli, Sharpe. — An imperfect example of this species in the Museum of Practical Geology (No. 0373), from the Lower Chalk of the Isle of Wight, also shows a portion of the anterior border of one of the muscular scars (PI. 18. fig. 3), The specimen 84 jNlE. G. C, CETCK ON THE MUSCULAE ATTACHMENT OP THE consists of the natural cast of only two wliorls. The aperture is not preserved, but a portion of the last whorl without doubt formed part of the body-chamber. The larger whorl is 30 mm. high (/. e. from the lowest row of tubercles to the suture of the shell), and measures 65 mm. from side to side. The anterior border of the muscular impression occurs as an impressed line very near the anterior end of the specimen. Viewing the specimen with the large whorl downward, this line commences a little below the middle of the whorl, and, crossing the uppermost of the three rows of small tubercles, turns somewhat aln'uptly to the right, becomes more deeply impressed, and Avith a bold anteriorly-convex curve crosses the other two rows of small tubercles and passes on to the sloping surface below the tubercles, being intercepted at about 11 mm. below the lowest row of tubercles by the broken anterior end of the specimen. Although the impression in this specimen is very incomplete, it serves to confirm the structure which has just been described in Turriliies tuberculatus. Subg. Heteroceras, d'Orbigny. Turrilites (Heteroceras) polyplocus, Roemer. — It is exceedingly interesting to have been able to recognize any indications of the muscular attachment in this subgenus of Ttirrilites, since here the shell is coiled in the opposite direction to that of the genus Turrilites, and hence a corresponding inversion of the muscular attachment was to be expected. The examj)le of Turrilites {Heteroceras) ^joIijjUocks, Eoemer, in which the attachment has been seen forms part of the British Museum Collection (No. 461-51) and is from the Upper Cretaceous rocks of Haldem, Westphalia (PI. 18. fig. 4). The specimen consists of about one and a half whorls. The aperture is exceedingly well preserved, but the suture-line is not shown, so that the base of the body-chamber cannot be thereby recognized. The form of the right side of the attachment is seen in fig. 4. Viewing the specimen as represented in the figure, the line indicating the anterior boundary of the muscular attachment is seen as an impressed line to commence on the lateral area of the whorl just to the riglit of the tubercle, which is above and somewhat to the left of the aperture ; passing downward it turns to the left immediately under the tubercle, and continues to pass downward for rather more than 20 mm. ; having turned upward very slightly, it continues as a line of colour in a broad sweep, nearly parallel to the outer curve of the whorl, to within about 60 mm. of the border of the aperture, when it again becomes a finely-incised line ; then, turning upward and still passing forward for about another 20 mm., it curves somewhat abruptly backward, continuing for about 20 mm. ; this last portion of the line enclosing an oval area, open posteriorly, the diameters of which are 20 and 12 mm. respectively. This area I regard as one of the muscular scars, and the line leading up to it as being partly the boundary of tlie shell-muscle, and partly the boundary of the annulus. It is much to be regretted that in developing the specimen its surface was somewhat scratched and rubbed, so that it is not possible satisfactorily to foUow the course of the impression on the other side of the whorl. ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 85 AMMONITES *. Amaltheid ,e, p. Fischer. OXYNOTICERAS, A. Hyatt. Oxynoticeras^ sp. — The example (PL 18. figs. 5, 6) apparently referable to this genus, in Tivhich the form of the muscular attachment has heen observed, is from the Great Oolite (Stonesfield Slate) of Stonesfield, Oxfordshire, and forms part of the British Museum Collection (No. 36710). It has been labelled "Ammonites discus, .7. Sowerby," but it is jjrobably not referable to Sowerby's species f , although its state of preservation does not allow an accurate determination. It is a crushed, poorly-preserved, internal cast lying loose on a piece of matrix. The greater part of the specimen is septate ; the body- chamber has been broken across obliquely, but fortunately the posterior portion is preserved. When complete the specimen probably was quite 145 mm. in diameter, and its umbilicus about 22 mm. wide. The last half-whorl at least was occuj)ied by the body-chamber, the base of which is o2"5 mm. high and about 10 mm. thick. The anterior border of the muscular scar and of the anuulus can be traced across each side of the specimen, but it is more distinct on that side (flg. 5) lying upon the matrix. Here the anterior border arises from the suture of the shell at a distance of 115 mm. in advance of the last septum ; after passing forward and outward for a short distance it turns backward in a rather broad curve, and passes uninterruj)tedly across the body-chamber in a i'airly straight line, which is almost parallel to the general direction of the last septum, being in advance of the septum 15'5 mm. on the inner portion of the lateral area and 21 mm. near the periphery, where it seems to turn backward a little, but this appeai'ance may be due to the much-compressed state of the fossil ; it has no depressions corresponding to the lobes of the suture-line. The portion of the border to a distance of about 13 mm. from the inner edge of the whorl is indicated by a well-marked depressed line, and the rest of the border is indicated by the anterior boundary of a band of colour about 4-5 mm. wide, the posterior boimdary of which is not sharply defined. The inner portion, bounded anteriorly by the depressed line, doubtless rejn-esents the muscular scar, and the broad band of colour the anuulus ; the scar exhibits distinct lines of growth. On the opposite side the muscular scar and annulus are less clearly defined. The muscular impression appears to be somewhat nearer the last septum, for its anterior boundary arises as a faintly-incised line at a point only S'5 mm. in advance of the last septum, and passes outward and backward as far as the septum, wliich it meets at a distance of 8'5 mm. from the inner edge of the whorl. Before reaching the septum, i. e. at a distance of 3-5 mm. from the septum, this boundary gives off a branch (indicated by a line of colour) which can be traced as a slightly- waved line across the body-chamber to the periphery, where it meets the anterior boundary on the opposite side. The portion of the annulus adjoining the muscular impression ou this side is only about * The nomenclature and grouping of the Ammonites here adopted are those given by Prof. Dr. K. A. v. Zittel in his ' Grundzuge der Palaontologie," 1895. t J. Sowerby, ilin. Con. vol. i. p. 37, pi. xii. (1813). 86 MR. G. C. CRICK ON THE MUSCULAR ATTACHMENT OP THE 1'5 mm. wide for a lengtli of about 8'5 mm. ; it then expands somewhat rapidly to a width of 4'5 mm., a width which it maintains across the rest of the body-chamber, joiniog the band on the opposite side, the portion near tlie periphery being, however, somewhat less distinct than the rest. The discrepancy in the position of the two impressions is doubtless due in a great measure, if not entirely, to the crushing which the specimen has undergone during fossilization. Amaltheus, Montfort. Amaltheus spinatus, Bruguiere, sp. — The muscular impression has been observed in an example of this species in the British Museum Collection (No. C. ''919), the locality of which is not recorded. The specimen consists of the well-preserved septate portion of the shell, together with a natural cast of one side of the dorsal (or inuer) part of the posterior portion of the body- chamber (PI. 18. fig. 7). The dimensions of the sjieciraenat the base of the body-chamber are : — diameter of the shell 57 mm. ; width of umbilicus 24 mm. ; height of outer whorl 19 mm. ; ditto above preceding whorl about 17 mm. ; thickness of outer whorl (excluding ribs) 19 mm. ; ditto (including ribs) 22 mm. A portion only of the anterior boundary of the muscular impression is preserved. Tliis, Avhich appears as an impressed line, arises almost close to the suture (of the shell) 9 mm. in front of the anterior part of the small saddle belonging to the last suture-line that is situated on the edge of the umbilicus ; it curves outward and backward for a distance of about 5 mm. where it is about 4 mm. from the suture (of the shell) ; then, passing backward nearly parallel to the inner edge of the whoid, it appears to divide just before meeting this small saddle, one part passing on the inner (dorsal) side of the small saddle situated on the edge of the umbilicus and then disappearing, the other passing on the outer side of the same saddle and then also disappearing. Posterior to this distinctly-impressed line there are several very faint lines coacenti'ic with it. Cardioceras, Neumayr & Uhlig. Cardioceras excavatum, J. Sowerby, sp. — In the description of the annulus, which has already been given, I have described the muscular attachment in an example of this species (see ante, p. 75). Another example of this species is also figured which shows the course of the anterior l)0imdary of the muscular scar on the dorsal or impressed portion of the whorl (Pi. 19. figs. 1, 2). Cardioceras aff. excacato, J. Sowerby, sp. — The muscular impression is also shown in an example of Canlioccras in tlie Britisli Museum Collection (No. 50098), but its locality is not recorded (PI. 18. figs. 9, 10). It is, however, allied to Card, excavatum, but is more comjiressed and more widely umbilicated than that species. The dimensions of the specimen are : — diameter of shell 54 mm. ; width of umbilicus 18'5 mm. ; height of outer whorl 20 mm. : thickness of outer whorl 12 mm. The test has been removed ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 87 from tl)e greater part of the body -chamber, and the latter can fortunately be removed from the rest of the specimen. The whorl is carinate, subquadrangular in transverse section, its sides mnch flattened and nearly jiarallel to each other ; at the base of the body-chamber it is 13'5 mm. high and 10 mm. thick. On the left side of the specimen (PI. 18. fig. 9), near the base of the body-chamber a feebly-impressed (on the internal cast) line arises from the suture of the sliell [i. e. the inner edge of the whorl) 4'5 mm. iu front of the last septum ; it extends outward and backward almost as far as the septum, nearly reaching the same at the inner side of the second (or inferior) lateral lobe ; it then turns outward, as if to pass over the adjoining saddle, and soon disappears. When the body-chamber is detached (PL 18. fig. 10) this incised line is seen to be continued on to the impressed zone, being also indicated by a difference of colour, the portion posterior to the boundary being much lighter than the rest of this surface. Prom the edge of the Avhorl this boundary passes a little backward in an /"-shaped curve nearly to the central line of the im2:)ressed area, when, turning abruptly backward, it passes nearly parallel to the median line of this area as far as the small saddle adjoining the antisiphonal lobe. The corresjjonding line on the other side of the impressed area iias the same form, so far as it can be traced, but the edge of the whorl on this side is somewhat imperfect. A line of coloiu" apj)ears to indicate that the median space between the two boundaries was bridged over anteriorly. Tlie form of the muscular attachment just described on the impressed area of the outer whorl is confirmed by its appearance on the inner surface of the dorsal portion of the test of the body-chamber, which remains attached to the l)receding whoii. The muscular scar on the right side of the body-chamber is not preserved, the inner portion of the base of the body-chamber having been broken off. On the middle of the left lateral area there is a linguiform space, 8 mm. long and ■1 mm. broad, enclosed by a very faint line, open behind and convex anteriorly (PI. 18. fig. 9). Its lateral boundaries are nearly parallel to the inner and outer margins of the whorl respectively, the inner being l-'o mm. distant from the inner margin, and the oiiter at the same distance from the periphery of the whorl. The inner boundary passes just into the inferior lateral lobe along its outer side, and the outer boundary just passes into the superior lateral lobe along its inner side. There is a similar linguiform area on the middle of the right side of the body-chamber, 95 mm. long and 6 mm. wide, oj)en behind, and Avith a convex anterior boundary. Its inner boundary passes just into the inferior lateral lobe at its outer side, whilst the outer boundary passes just into the superior lateral lobe along its outer boundary, and not its inner, as on the opposite side of the body-chamber. Hence the linguiform area on this side is somewhat broader than that on the left side, the inner boundary being at about the same distance from the inner edge of the whorl, while the outer is nearei the periphery than on the opposite side. Only in this one specimen have these linguiform areas been observed ; but, as they are so distinctly displayed on both sides of the fossil, it is just possible that they are connected with the attachment of the animal to its shell. This example seems to support the figure given by Trautschold. SECOND SF.KIES. — ZOOLOGY, VOL. VII. 13 88 MR. G. C. CEICK ON THE MUSCULAR ATTACHMENT OF THE Cardiocerm Sidherlandice, J. cle C. Sowerby, sp. — The position of the anterior boundary of the sbell-muscle is exceedingly well shown in a large example of this species from the Oxfordian of Scarborough, Yorkshire. It forms part of the British Museum Collection (No. 82369). It is a large internal natural cast, about 370 mm. (or nearly 14f inches) in diameter, the umbilicus being 85 mm. in diameter, and having almost perpendicular walls. Nearly one-half of the outer whorl is occupied by the body- chamber, the base of wbich is obtusely cordate in section, 132 mm. (or nearly 5| inches) high and 210 mm. (or rather more than 8J inches) wide, the inner area being 45 mm. wide and nearly perpendicular to the plane of symmetry of the shell. The anterior boundary of the muscular impression, represented by a well-marked groove, crosses the umbiUcal margin 60 mm. (or about 2| inches) in front of the last septum, and passing outward and backward becomes much less distinct at about 52 mm. from the last septum, and at about the same distance from the umbilical margin. It appears, however, to be continued across the whorl by a faint, somewhat irregular groove, which, originating some 6 mm. posterior to the groove just described, crosses the whorl in a flat forwardly-concave curve which is only 15 mm. from the anterior portion of the lateral saddle, and nearly touches the anterior part of the external saddle ; this we regard as the anterior boundary of the annulus. Passing inward from the umbilical margin, the boundary of the shell-muscle is indicated by a distinct groove which curves somewhat backward, but can be traced onlj'^ about halfway across the inner area of the whorl. Cardioceras funifermn, J. Phillips, sp. — A similar boundary of the shell-muscle has been observed in several examples of this species which are contained in the British. Museum Collection. It is well shown in an example (No. 50447) from the Oxford Clay" of Trowbridge, Wiltshire. This is 167 mm. in diameter and 68 mm. thick, the umbilicus being almost closed and its margin rounded. About one-half of the outer whorl is occupied by the body-chamber, the base of w^hich is acutely cordate in section, 64 mm. wide and 72 mm. high. On the left side of the specimen the anterior border of the shell-muscle is indicated by a groove which crosses the umbilical margin at 9 mm. anterior to the last septum ; passing backward and outward as a fairly wide groove for about 10 mm., it then becomes shallower and wider. The posterior boundary of the muscular scar is represented by a slightly raised ridge, which, passing from the umbilical margin just above the last septum outward and forward, meets the lower boundary of the anterior groove at a point 12 mm. from the umbilical margin. The anterior groove appears to be continued across the whorl {i. e. to within 5 mm. of tiie periphery) as an exceedingly faint groove, which indicates the position of tlie anterior border of the annulus ; this is 8 mm. anterior to the lateral saddle, 10 mm. anterior to the external saddle, and is depressed at each lobe. On the outer haK of the lateral area of the whorl this boundary is partly indicated by remains of the test. On the right side of the specimen there are similar indications of the anterior boundary of the muscular scar, but uo traces of the annulus. ANJMAL TO ITS SHELL IX SOME FOSSIL CEPHALOPODA, 89 Cardioceras sj). — Indications of the muscular attachment are well displayed in a small Ammonite from the Upper Jurassic of Kintradwell, Sutherland, which forms part of the British Museum Collection (No. C. 4389). Although the specimen is fairly well pre- served, I have not been able satisfactorily to determine the species, but it seems to be referable to the genus Cardioceras (PI. 19. figs. 3, 4). Its dimensions are as follows : — diameter of shell 235 mm. ; greatest thickness 8'5 mm. ; width of umbilicvis 7 mm. ; height of outer whorl 8 mm. The last two-fifths of the outer whorl are occvipied by the body-chamber ; the test having been removed from the left side and from the periphery of this portion of the whorl, the internal cast is weU displayed. Unfortunately only a small portion of the last suture-line can be made out, the rest being obscured by the test. The portion of the last septum adjacent to the suture of the shell is obscured, but on the internal cast of the body-chamber, at a short distance anterior to the last septum, a very fine incised line arises from the suture of the shell, passes inward in an almost radial direction for about 2'5 mm., then turns I^ackward for about 0-5 mm., and again resumes its radial direction across the whorl, being feebly depressed as it passes over each lobe, and slightly raised in passing over each saddle; it is about 0"5 mm. above the lateral saddle and almost touches the most anterior portion of the external saddle. As it approaches the periphery it lu^rns forward to join a somewhat peculiar-shaped roughened scar represented in fig. 4, the posterior inflated portion of which is rather rougher than the rest. Unfortunately the opposite side is obscured by matrix. The perijihery of the posterior portion of the body-chamber seems to be somewhat deformed, and to possess a feeble keel with a shallow sulcus on either side ; this deformation may account for the median division of this scar, which probably was originally horseshoe-shaped, as observed in several otlier Ammonoids. The portion of the incised line near the suture of the shell doubtless represents the position of the anterior border of one of the shell-muscles, the rest of the line indicating the position of the anterior boundary of the annulus, there having been, in addition, a firm attachment at the centre of the 2:)eriphery. Neumaykia, Xikitiu. Nenmayria catenulata, Fischer, sp. — In the British Museum Collection there is an example of this species exhibiting the form of the muscular attachment. It is a badly- cruslied internal cast from the Portlandian of Choroschowo, near Moscow, Russia. The specimen is 119 mm. in diameter, the width of the umbilicus (from suture to suture) being 18 mm., the height of the outer whorl 58 mm., and its thickness 26 mm. The inner area of the whorl slopes towards the umbilicus and at the base of the body-chamber is 6 mm. wide, the height of the whorl here being 43"5 mm., and its greatest thickness, which is at a short distance from the umbilical margin, 15-5 mm. Tlie last two-thirds of the outer whorl are occupied by the body-chamber. The whorl is sagittate in cross section. The muscular impression is well shown on one side, but tlie crushed condition of the specimen has obliterated it on the other side. Arising from the suture at about 7 mm. from the base of the l)ody-chamber, the boundary of the impression, in the form of a faintly-indented 13* 90 MR. G. C. CRICK 0]S THE MUSCULAR ATTACHMENT OF THE line, passes outward and backward in a curve, which nearly meets the last septum at about ll'Onim. from the suture, and thus encloses a subtriangular area on the inner side of the base of the body-chamber. Just before this outer line reaches the last septum it gives off a very faint branch which passes outward towards the periphery, but can be traced for a very short distance only. This is, without doubt, an indication of the anterior boundary of a portion of the annulus. Within and parallel to the outer boundary of the impression there are one or two very faintly indented lines. TissoTiA, Douville. Tissotia Uwaldi, v. Buch, sj). — The muscular impression is shown iu an example of this species in the British Museum Collection (No. C. 4810 a) from the Chalk (Senonian) of Mezab-el-Mesai, Algeria (PI. 18. fig. 11). The specimen is a natural cast, 8S'5 mm. in diameter ; rather more than one-fourth of the outer whorl is occupied by a portion of the body-chaml)er, but this latter is somewhat imperfect on one side, so that the dimensions of the specimen can best be taken at the base of the body-chamber. Here its dimensions are as follows : — diameter of shell 84'5 mm. ; width of umbilicus 8'5 mm. ; height of outer whorl 42 mm. ; greatest thickness of same (at a short distance from the umbilicus) 47 mm. The whorl is obtusely cordate in transverse section, rather wider than high, and indented to rather more than one-half of its height by the preceding whorl. The anterior border of the muscular impression is represented by a feebly-incised line. It cannot be traced quite as far as the suture of the shell, but on the narrow inner area of the whorl it is 4 mm. from the last septum ; passing thence forward and outward on to the lateral area, it attains its greatest distance from the last septum (viz. 8"5 mm.) at 4 mm. from the edge of the whorl. Then, curving backward, it passes on the vimbilical side of, and at a distance of 1'5 mm. from, the first (counting from the umbilicus) large lateral saddle, and, turning forward, sweeps round in an anteriorly-concave curve immediately about the small saddles occupying the margin of the umbilicus and soon disappears. The muscular scar thus bounded appears to have been an oval about 10 mm. by 7 mm., its longer axis being placed nearly in a radial direction but slightly inclined backward. Prom the anterior portion of the boundary of this impression a feebly-depressed line passes backward and outward in a broad f or wardly- convex curve to within about 2*5 mm. of the outer portion of the first (counting from the umbilicus) large lateral saddle, then in a forwardly-concave curve crosses the adjacent lobe, and disappears just above the next lateral saddle. This line may indicate a portion of the anterior boundary of the annulus. The opposite side of the body-chamber has been so much eroded that the muscular impression is not preserved. A^'IMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 91 Lytoceratid^, Neumayi", emend. Zittel. Lytoceras, Suess. Lijtoceras cornucopia;. Young & Bird, sp. — The impression of one of the slicll-muscles has been observed in an example of this species in the British Museum (No. 37851) from the Upper Lias of Whitby, Yorkshire (PI. 19. figs. 15, 16, 17). The dimensions of the specimen are : — diameter 22 mm. ; width of umbilicus 8 mm. ; height of oviter whorl 8 mm. ; greatest thickness of the outer whorl 8 5 mm. Rather more than one-half of the last whorl is occupied hj the body-chamber, the base of which is nearly circular, its dorso-ventral and transverse diameters being each G mm. The amount of indentation by the preceding whorl is very small. At the base of the body-chamber, and on the inner area of the whorl, tliere is an oval impression (fig. IG), truncated on the inner side by the ed-TC of the " impressed zone." The diameters of the portion that can be seen are 1-75 mm. and 2'0 mm. respectively, the longer diameter being placed transversely on the whorl. The anterior and the posterior boundaries are both visible, the latter l)eing almost close to the first auxiliary saddle ; but no trace of the annulus can be seen. On the peripheral area there is an elongated linguiform impression (fig. 17), which is rounded and submucronate anteriorly, but is open posteriorly, each limb being situated in each half of the siphonal (periphei'al) lobe. Its anterior portion is a little in advance of the most anterior part of the siphonal saddle ; its posterior portion is slightly contracted. Its length is 3'25 mm. and its width (between the limbs) '75 mm. In the British Museum Collection there is also a portion of the natural internal cast of the body-chamber of another example of this species (PL 19. figs. 13, 14), from the Upper Lias of Whitby, which exhibits the impression of the boundary of the right muscular scar surrounded anteriorly and laterally by a dark-coloured, longitudinally-elongated, oval area, a portion of which is slightly rougher than tlie rest. Its form is shown in fig. 13. Only the right side of the base of the body-chamber is preserved, the heiglit of the whorl here being 35 mm. At about 4'5 mm. anterior to the last septum, the incised line indicating the position of the boundary of the muscular scar passes fi-om the suture of the shell — /. e. the edge of the impressed zone — in a radial direction for about 7 mm. ; then, turning abruptly backward nearly at right angles to its former course, it is continued as far as the last septum. At the suture of the shell the boundary of the oval dark-coloured area is 3'5 mm. anterior to the incised line just mentioned ; after proceeding forward in an anteriorly-concave curve for about 2 mm., it passes in an anteriorly-convex curve forward and outward for about 7 mm. ; then, after curving gently backwai'd for about 5 mm., it can be traced nearly as far as the last septum, having a direction nearly parallel to the edge of the impressed zone. Lytoceras fimbriahmi, J. Sowerby, sp. — The muscular impression is also shown in a fragmentary example of this species in the British Museum (No. 20837) from the Middle Lias of Kilsby Tunnel, Northamptonshire. The specimen consists of nearly half a whorl, and is a natural cast of part of the body-chamber of a shell having approximately the 92 MK, G. C. CBICK ON THE MUSCULAR ATTACHMENT OF THE following dimensions : — diameter 120 mm. ; width of umbilicus 49 mm. ; height of outer whorl 44 mm. ; greatest thickness of ditto 41 mm. The posterior portion of the body-chamber is preserved ; one side is much crushed, but the rest is fairly comjilete. A portion of the test still adheres to the cast. The sjjecimen, measured along the median line of the periphery, is 165 mm. long ; its transverse section is ovate, the greatest thickness being at about two-fifths of the height of the whorl from the inner edge ; at its posterior end the height of the whorl and its thickness (allowing for the crushing) are 80 mm. and 27 mm. respectively. The impression of one shell-muscle is well shown, but only the inner portion of the other (PI. 19. figs. 11, 12). The whorl is very slightly imj^yressed by the preceding whorl. In shape the impression is truncated-oval, its longer diameter being transverse and tlie truncated end towards the median line of the dorsal surface. Arising a little in advance of the saddle on the side of the antisiphonal lobe, the boundary of the impression passes forward for about 5 mm. nearly parallel to the median line of the dorsal or antisiphonal surface, and at 1'5 mm. from its fellow on the opposite side ; then, curving outward, it extends for about 10 mm. ia a direction almost at right angles to its previous course; bending rather abruptly backward, it jiasses for a short distance nearly parallel to the boundary of the impressed zone ; tehn, curving inwai'd and backward, it speedily disappears. The greatest width (transverse) of the impression is 12 mm. There is no trace of the annulus. The boundary of the impression is indicated by a depressed line, Avhich is rather deejily incised on the inner and outer portions, but somewhat less so on the anterior portion. The portion of the surface of the cast bounded by tlie impression is a little rouglier than the rest. Owing to the crushed condition of the whorl, only the inner portion of the other impression is preserved. The impression is so situated that in a lateral aspect of the whorl only a very small portion of it can be seen (fig. 12). Lytoceras qiuidrisulcatimi, d'Orbigny, sp. — One example of this species, collected by Dr. J. W. Gregory in East Africa, exhibits a portion of the muscular impressions. It is a crushed fragment of a natural cast of the posterior pai"t of the l)ody-chamber. The inner portion of the whorl is badly crushed, but exhibits on either side a part of the muscular scar. At the base of the body-chamber the whorl is 30'5 mm. high and 80 mm. thick, the greatest thickness being a little within the central portion of the lateral area ; tlie transverse section is therefore nearly circular. The muscular scars are somewhat darker than the surrounding surface of the cast, and present a slightly roughened appearance. That on the left is the better shown, but its inner portion is obscured so that the "whole of its anterior border is not visible. Its bovmdary is usually a feebly- indented line, but sometimes a slightly-raised line. Tiie anterior boundary of this impression appears to commence at about 7'5 mm. in advance of the most anterior part of the last septum, and about 8 ram. from the central line of the impressed zone; it passes thence slightly forward and outw^ard for a distance of about 2 mm. ; then, curving backward at about 10*5 mm. from the median line, it passes for a short distance nearly parallel to the median line ; then, at about 4'5 mm. in advance of the last septum, ANIMAL TO ITS SHELL IX SOME FOSSIL CEPHALOPODA. 93 curving rather abruptly inward but still passing backward, it disappears at about 5'5 mm. from the median line, exlni)iting, however, a tendency to again turn forward. The portion of the scar which is visible has a pyrifortn shape ; its axis is at an angle of about 45° with the median line of the dorsal area of the whorl, the '"stalk" being- directed outward and backward ; its length is about 8'5 mm., and its gi'catest width about 5 mm. The other scar is truncated by a fracture crossing it obliquely, so that only the posterior portion of the impression is seen. It is somewhat darker than the surrounding surface, and bounded anteriorly and laterally by a very slightly-raised line. Commencing from the fracture at about 9 mm. in advance of the most anterior part of the last septum, and at the same distance from the median line of the dorsal area, the anterior boundary passes backward and very slightly outward ; then, curving round, comes to within 2 mm. of the suture-line ; then, curving inward and forward, it is again intercepted by the fracture at about 4 mm. from the median line. The anterior and outer boundaries of the impression are sharply marked by a feebly-incised line, but the posterior boundary is not quite so sharply defined. There is a very shallow and rather broad depression on the peripheral area about 5 mm. in front of the summit of the siphonal (peripheral) saddle ; on either side of the median line of the periphery, and at a distance of 3 mm. apart, a very faint line curves forwai'd and towards the median line of the periphery, nearly meeting its fellow at about 3 mm. anterior to the depression just mentioned. This possibly represents the anterior border of the peripheral portion of the annulus. JiIgoceratid.'E, Neumayr, emend. Zittel. Arietites, Waagen, emend. Zittel. Arietites ohtusus, J. Sowerby, sp.* — The muscular impression is well shown in an example of this species from the Lower Lias of Lyme Regis, that was kindly lent to me by Mr. G. F. Harris, F.G.S. The specimen is a fairly-complete internal cast, almost entirely denuded of the test. Its dimensions are : — diameter of shell 101 mm. ; width of umbilicus 43 mm. ; height of outer whorl 32 mm. ; ditto above preceding whorl 29 mm. ; greatest thickness (excluding ribs) 30 mm. ; ditto (including ribs) 33 mm. The dimensions of the base of the body-chamber are : — height of whorl 26 mm. ; thick- ness (excluding ribs) 22 mm. ; ditto (including ribs) 25 mm. The body-chamber is complete and occupies the last half-whorl. The muscular impression is situated at the base of the body-chamber and occupies the inner area of the whorl (PI. 19. figs. 8, 9, 10). Its anterior boundary, represented by a fine incised line, is convex, its anterior portion being 16 mm. in front of the anterior portion of the second lateral saddle of the last septum. Passing backward its outer boundary is nearly parallel to, and at a distance of 6 mm. from, the suture (of the shell). It can be traced backward for a distance of * Min. Con. vol. ii. p. 151, pi. clxviii. (l'6\'l)= Asteroceras ohtusum (J. Sowerby): fide Hyatt, 'Genesis Arietidse,' 1889, p. 201. 94 MK. G. C. CRICK ON THE MUSCULAE ATTACHMENT OF THE 11 mm., beyond which point the surface of the cast is fractured. About 2 mm. behind this line, and nearly concentric with its anterior portion, tliere is another very faint line, evidently marking a former attachment of the shell-muscle. On the inner area of the Avliorl there are three or four fine, faint, longitudinal grooves, extending over three-fourths of the length of the body-chamber; one of these, 2 mm. from the suture (of the shell), extends the whole length of the body-chamber. On the periphery, on either side of the median line, there is a feebly-impressed sigmoidal line (fig. 10), tlie anterior portion of which is about 11 mm. in advance of the anterior portion of the external (peripheral or siphonal) saddle. Each line arises about 2 mm. from the median line of the periphery ; it passes away from this line, and backward to about 8 mm. from the most anterior portion of the external (peripheral or siphonal) saddle, and then disappears. These lines may indicate the position of the attachment of the animal to this part of its shell, but no connection can be seen between these lines and the impressions on the inner area. A line drawn from the centre of the shell to the most anterior part of these lines on the periphery crosses the inner edge of the outer whorl at a point 7"i3 mm. posterior to the anterior boundary of the impression which is seen on the inner area. Posterior to these lines on the peripheral area there is a horseshoe-shaped marking with nearly parallel sides, each of which passes posteriorly into each half of the sijjhonal lobe. It is rounded anteriorly, and crossed in its length by several lines parallel to the anterior border. Its length (above the small median saddle) is 11 mm., and its width 5 mm. This may, or may not, be connected Avith the muscular attachment of the animal, but similar impi'essions have been observed in other forms. (See jEgoeeras capi'icorn/iij/, p. 95.) Arietites rarlcostatus, Zieten, sp.*- — In the British Museum Collection there is an example of this species (No. 0.4882) showing the muscular impressions (PL 20. figs. 10, 11). The locality of the specimen is not recorded, but, judging from the matrix, it came pro- bably from the Lower Lias of Somersetshire. The specimen is a well-preserved natural cast with the following dimensions : — diameter 51 mm. ; Avidth of umbilicus 33 mm. ; height of outer Avhorl 10 mm. ; greatest thickness of outer whorl (excluding ribs) 14 mm.; ditto (including ribs) 16 mm. The body-chamber occupies the whole of the last whorl, and its posterior part {ah) can be removed from the rest of the fossil; its transverse section is transversely oval, its thickness (excluding the height of the ribs) being 10 mm., and its height 7 mm.; it was only slightly indented by the broad periphery of the preceding whorl. The greater part of the muscular impressions is on the concave dorsal area, i. e. on the impressed zone. On either side of the median line of this area (fig. 11) there is a subti'iangular impression, having its broadly-rounded apex directed forward. These impressions are about 1 mm. apart, that on the right side of the shell being the more nearly complete. Each is bounded by a faint double fine. Commencing * F. Zieteij, Vcrsteia. Wiirt. p. 18, \>\. siii. f. 4 = Caloceras rarkostatum {Ziitien), Jidi Hyatt, Gen. Arietidae, p. 144. ANIMAL TO IT.S SHELL IN SOME FOSSIL CEPHALOPODA. 95 at the most anterior part of the antisiphonal (or antiperipheral) saddle and at a point 0'5 mm. from the median line, the boundary of the more nearly complete impression 2)asses forward and outward until it is 3 mm. in advance of the last septum and about 2 5 mm. distant from tlie median line ; then, turning backward and passing still outward, it apj)roaches the last sejitum, and nearly (but not quite) meets the inner portion of the lateral saddle, where it disappears, its place of disappearance being 4*5 mm. from the median line of the dorsal area or of the impressed zone. The outer boundary of the muscular impression is on the edge of the umbilicus, and therefore in a lateral view of the Ammonite only the outer backwardly-directed portion of the impression can be seen. There is a corresponding and similar impression on the other side of the specimen, but it is not so complete, owing to a fracture of the fossil. There are no traces of the annulus. JiIgoceras, Waagen, emend. Zittel. JEcjoceras cajjricornum, Schlotheim, sp. — A portion of the im2")ression of the muscular attachment of the animal has been observed in an example of this species from the Lias of Cheltenham, that forms part of the British Museum Collection (No. 67929). The specimen is a well-preserved natural cast, bearing portions of the test in a soft, white, friable condition (PI. 20. fig. 2). By removing this with a stiff In'ush from near the base of the body-chamlier, the muscular impression is well shown on either side. The dimensions of the specimen are as follows : — Diameter of shell (including ribs) 47 mm. ; ditto (excluding ribs) 44 mm. ; width of imibilicus 20 mm. ; height of outer whorl (including ribs) 15 mm. ; ditto (excluding ribs) 14-5 mm. ; thickness of whorl (including ribs) 17 mm. ; ditto (excluding ribs) 14-5 mm. At the base of the body-chamber the height and thickness of the whorl are respectively 11 and 13 mm. including the ribs, or 10 and 10"5 mm. excluding the ribs. The outline of the muscular impression is seen on either side at the base of the body-chamber and quite close to the suture of the shell. It is convex anteriorly, its anterior boundary being 6 mm. in front of the most anterior jwrtion of the second lateral saddle ; its outer boimdary is nearly parallel to, and at a distance of 2 mm. from, the edge of the impressed zone, and passes jiosteriorly on to the outermost branch of the second lateral saddle. Its anterior boundary exhibits a tendency to curve forward at the suture of the shell. In the middle of the jieripheral area there is a tongue-shaped scar, which is rather more than twice as long as wide, has nearly parallel sides, and is rounded anteriorly ; each side of it just touches the boundary of the siphonal lobe. The scar seems to have been covered with a thin film of shelly matter, for j)art of this has been broken away from the anterior portion so as to expose a black layer beneath. This scar would be situated in the immediate neighbour- hood of the siphuncle, and may or may not have had anything to do with the muscular attachment of the animal. Its length above the extremity of the small median saddle is about 6 mm., and its width is 1"5 mm. A precisely similar scar has been observed in Arietites obtiisns*. * See ante, p. 93. SECOND SERIES. — ZOOLOGY, VOL. VII. 14 96 ME. G. C. CRICK ON THE MUSCULAE ATTACHMENT OF THE The outline of the musculav impression is also well shown in another example of this species from the Lower Lias, near Whitby, in the collection of F. L. Bradley, Esq., F.G.S., of Alderley Edge, Cheshire, to whom I am greatly indebted for the loan of the specimen. The impression has the same form and position as that already described in the example from the Lias of Cheltenham, which is in the British Museum Collection (No. 67929). The specimen is in the centre of a nodnlc ; its dimensions, so far as can be ascertained, are as follows : — diameter of shell 65 mm. ; width of umbilicus 31 mm. ; height of outer whorl 16 mm. ; ditto at base of body-chamber 13 mm. The last half-whorl is occupied by the body-chamber, the exposed portion of which is almost completely denuded of the test ; at its base and on the inner portion of the whorl the outline of the muscular impression can be seen. The anterior convex boundary of the impression is 5"5 mm. in advance of the last septum, the width of the impression from the suture of the shell being 2 mm. There is no trace of the annulus, and the perijiheral portion of the fossil is obscured by matrix. JEgoceras laqueolum, Schloenbach, sp.* — In an example of this species from the Lower Lias of Harbury, Warwickshire, in the British Museum Collection (No. C. 6619), one of the muscular scars is well displayed. The specimen consists of about three-fourths of a whorl 165 mm. in diameter, and is a natural cast of part of the body-chamber. The base of the body-chamber is complete : it is 24 mm. high ; 30 mm. wide including the ribs, or 29 mm. excluding the ribs. The muscular scar, which is clearly seen at the base of the chamber, is situated partly on the lateral area and partly on the impressed zone (PI. 20. figs. 3, 4). The faintly-incised line bounding the scar arises from the last sejitiim at a point 4"5 mm. from the inner edge of the whorl ; then, passing forward for a length of about 9 mm. nearly parallel to the inner edge of the whorl, it turns towards the impressed zone, becomes much more distinct, and crosses the inner edge of the whorl 13 mm. in advance of the last septum ; passing on to the impressed zone with a rather broad sweep, it gradually disappears, but the form of the scar is indicated by a difference in colour, the impression being a little darker than the surrounding surface. The impression did not quite reach the middle of the impressed zone ; it appears to have been elliptical in form, about 15 mm. long and 11 mm. wide, the larger portion being situated on the impressed zone. On the anterior portion of that part of the scar which is situated on the imjjressed zone there is an exceedingly faint line, concentric with the anterior border of the scar, which evidently marks a former attachment of the anterior border of the shell-muscle. Only a very small portion of the other scar is visible ; this is on the impressed zone. The greater part of the imjn-ession is obscured by matrix. There is no trace of the annulus. * raltcontogr. vol. xiii. pi. xxvi. f. \ = CaJoctras Uaskwn (d'Orbigny), _^c?e Hyatt, Geu. Arietida:, p. 139. ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 97 JEgoceras Portlocli'd, Wright. — An example of tliis species from the Boulder Clay of Ireland (exact locality iinkuown) was sent to me hy Dr. A. H. Foord for determination. It was in a reddish matrix. It is a natural cast of the posterior portion of the body- chamber, showing not quite the complete suture-line at its base, and bearing only fragments of the inner portion of the test. The length of the fragment measured on the periphery is just over 70 mm. ; the whorl is nuich comjjressed, nearly twice as high as wide ; the transverse section of the whorl is elongate-oval, its gi'eatest thickness being at about one-third of the width of the latei'al area distant from the suture (of the shell). The impressed zone on the inner side of the specimen shows that the indentation by the preceding whorl was very slight, and that the periphery of the jjreceding whorl was more acutely convex than that of the outer Avhorl. At the base of the body-chamber the height of the whorl is 33'5 mm., and the greatest thickness about 18 mm. Any indication of the muscular attachment that may be preserved on the surface of the impressed zone is obscured by portions of the test, but on each side of the inner portion of the lateral area of the posterior jioi'tion of the cast the impression of this attachment is to be seen. Its anterior boundary commences at a point on the edge of the impressed zone about 14 mm. in advance of the most anterior portion of the sutiire-line, /. e. the main or inner branch of the siphonal saddle ; it passes outward and backward for a length of about 5 mm., then for a short distance runs nearly parallel to, and at about 5 mm. from, the suture. After passing backward for a distance of nearly 10 mm. from its commencement, the line divides into two principal portions, one being continued almost parallel to, and only slightly approaching, the edge of the impressed zone, the other curving towards, and apparently reaching, the same edge at a distance of 11 mm. from its commencement. A fractui-e of the specimen prevents the former of the two lines being traced any further. About 1 mm. anterior to the incised line just described, there is a much fainter depressed line which, after extending backward for about 5 mm., nearly parallel to the incised line already described, appears to turn outward towards the periphery, and then quickly to disappear, vrhile posterior to the line already described, and also parallel to it, there are two or three much fainter lines. On the other side of the whorl there are lines corresponding to the principal incised line, and the line about 1 mm. anterior to it, but these can only be traced backward sonie G mm., owing to the crushed state of this side of the specimen. Near the base of the body-chamber, and slightly on the right side of the median line of the periphery, there is a horseshoe-shaped incised line having its convexity directed forward. Its anterior portion is 12 mm. in advance of the anterior portion of the outer branch of the siphonal (or peripheral) saddle. It is about 6 mm. long, 5 mm. wide in the anterior part, and 3"5 mm. wide in the posterior part. Each limb appears to be continued backward as far as the posterior end of the specimen, which is at about the level of the anterior portion of the outer branch of the peripheral (or siphonal) saddle, as a somewhat irregular, shallow, very faintly-impressed groove or grooves, each being almost parallel to the central line of the periphery. The posterior termination 14* 98 ]MK. G. C. CRICK ON THE MUSCULAK ATTACHMENT OE THE of each liinb is rather more deeply impressed than the rest. Within this horseshoe- shaped im])ressiou, and occupying- the median line, is a very fine incised line, which extends backward from about 1 mm. posterior to the anterior boundary of the impression for a distance of about 6'5 mm. Doubtless this horseshoe-shaped impression had to do with the muscular attachment of the animal to its shell, for it has been observed in other forms, but the present specimen does not enable us to trace any connection between this impression and the marks of the muscular attachment seen on the inner edge of the whorl. SoNNiNiA, Bayle. Sonninia sp. — In the British Museum Collection there is an example (No. C. 5188) of Sonninia sp. from the Inferior Oolite of Yeovil, Somerset, in which the impression of the shell-muscles can be seen (PI. 20. fig. 12). The test has been removed from the internal cast of the whole of the body-chamber, and the impression of each shell-muscle is displayed near the base of the chamber. The specimen has the following dimensions : — diameter of shell 91 mm. ; width of umbilicus (from suture to suture) 28 mm. ; ditto (from margin to margin) 37 mm. ; height of outer whorl 36'5 mm. ; greatest thickness (almost close to the umbilical margin) 24 mm., excluding thickness of test. The body- chamber occupies one-half of the last whorl ; at its base the whorl, or more correctly the internal cast of the whorl, is 27 mm. high and 19 mm. thick. The whorl is subquadrate in section, with nearly jjarallel sides and well-defined inner area, the latter at the base of the body-chamber being about 6 mm. wide and sloping towards the umbilicus, making an angle of about 140° with the lateral area. The boundary of the muscular impression is indicated by an incised line which appears on the inner area of the Avhorl at a point 10"5 mm. anterior to the last seiDtum; it jDasses outward and. backward, just crossing the subangular umbilical margin, on to the lateral area, being at about 6 mm. distant from the suture of the shell, and ajipears to almost touch the saddle of the last septum that is situated on the subangular umbilical margin. On the area enclosed by this incised line, and concentric with it, there are several very faint lines, similar to those seen in the impression of the shell -muscles in the recent Nautilus. The surface of the cast anterior and also exterior to this incised line bears a number of shallow and iiTegular indentations, which may have had something to do with the muscular attachment, but the incised line just described appears to have been the impression of the anterior and exterior boundary of the shell-muscle. A similar line and similar adjacent indentations are present on the opposite side of the cast, but no indications of the annulus have been observed in this specimen. H A R p o c E R A T I D M, Neumayr, emend. Zittel. Hecticoceras, Bonarelli. Meclicoceras hcnticnm, Reinecke, sp. — In the British Museum Collection tliere is an example (No. 22309 a) froiii the Brown Jura e, Dettingen, Wiirtemberg, which displays the impression of the muscular attachment on both sides of the body-chamber ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 99 (PI. 20. figs. 5, 6, 7). It is a natural cast, and has the following dimensions : — Diameter of shell 18'5 mm. ; width of umbilicus 7"5 mm. ; height of outer whorl G%j ; greatest thickness 4 mm. At the base of the body-chamber the whorl is 5 '5 mm. high and 3'5 mm. thick. The shell is somewhat comjjressed, the inclusion very slight, and the umbilicus wide and shallow. The body-chamber occupies rather more than one-quarter of the last whorl, its inner (dorsal) edge subtending a chord of 8 mm. on one side and a little less on the other side. Erom the fractured anterior end of the body-chamber a double feebly-impressed line passes backward at a distance of 1 mm. from the suture (tig. 6) ; then, diverging slightly, the two lines cross the whorl in a rather deep forwardly- concave curve, their greatest distance from each other being rather more than 1 mm. Approaching each other slightly, but without touching, they curve forward at the periphery, each forming a submucronate jioint before passing on to the other side. It is to be noted that these points are not in the median line of the periphery, but slightly ou one side (fig. 7). The posterior of the two lines crosses the lateral area about 1 mm. in advance of the anterior portion of the first lateral saddle. Ou the left side of the anterior end of the body-chamber (fig. 5) the double line just described curves slightly towards the periphery, but the opposite side, being a little shorter, does not exhibit this curvature. This double line probiibly represents a j^oi'tion of the anterior boundary of the shell-muscle, the two lines on the lateral and j^eripheral areas indicating the position of the anterior and posterior boundaries resijectively of the annulus. CEcoTiiAUSTEs, Waagen. CEcotrmistes crenatus, Bruguiere, sp. — Two examples in the British Museum Collection (No. 8968), from the Oxfordian of Doubs, France, exhibit what appears to be the muscular im2)ressiou. Both are natural casts. One (PL 20. fig. 9) of these (No. 8968 b) has the following dimensions (exclusive of the spines on the periphery) : — diameter 11 mm. : width of umbilicus 3 mm. ; height of outer whorl 5 ram. ; thickness of ditto 3 mm. At the base of the body-chamber the height of the whorl is 4 mm., and its thickness 2"5 mm. The septate part of the shell and the extreme base of the body-chamber are of a reddish-brown colour, while the rest of the body-chamber is of a much darker shade, a dark and very distinct line marking the division near the base of the body-chamber. This line appears to be the anterior border of the muscultir attachment of the animal. It commences from the suture only a short distance in advance of the last septum, and crosses in a radial direction the inner half of the lateral area until reaching the lateral saddle where it is 0*75 mm. in advance of the suture-line ; it then curves slightly backward, making a very shallow curve, uatil it reaches a point about 1'25 mm. from the median line of the periphery, where it turns somewhat abruptly forward, and reaches the median line of the periphery, 2*25 mm. \\\ advance of the summit of the outer (or peripheral) saddle, thus forming on the periphery a subtriangular projection. A precisely similar line is seen on the opposite side of the cast, but in tliis species there does not apjiear to be any forAvard prolongation near the 100 ME. G. C. CEICK OX THE MUSCULAE ATTACHMENT OE THE inner area of the whorl such as has been observed in Distichoceras Bcmgieri (see below) and Hecticoeeras hecticmn (see p. 98). The other specimen (No. 896S a) has the following- dimensions, exclusive of the periphei'al spines, which in this example are comparatively small : — diameter of the shell 11 mm. ; width of umbilicus 2 mm. ; height of outer whorl 5-5 mm. ; thickness of ditto 2'5 mm. At the base of the body-chamber the height of the whorl is 4"25 mm. (exchiding spines), and the thickness 2'5 mm. The state of preservation of this- specimen is quite similar to that of the one just described ; the dark line near the base of the body-chamber, which is most prol)ably the anterior boundary of the mxiscular attachment, is very like that in the previous specimen, but is slightly more waved on the lateral area. In this example also there does not appear to be any forward prolongation of the muscular impression on the inner {not impressed) area of the whorl. The lack of any forward prolongation in this species seems to be confirmed by a specimen (No. 19536 e) in the British Museum Collection, from the Drift of Braunstou, Northamptonshire, in which there is au indication of the anterior boundary of the muscular attachment near the su.ture of the shell, and in this example also it is only a short distance anterior to the last septum. Distichoceras, Munier-Chalmas. Bistichocoras Bangicri, d'Orbigny, sp. — In the British Museum Collection there are two examples (No. 5140 a, b) of this species which clearly display the form and position of the muscular attachment of the animal to its .shell. The species occurs in the Oxfordian, but the locality of these specimens is not recorded. In the larger example (No. C. 5140 a) rather more than one-half of the last whorl is occupied by the body-chamber (PI. 20. fig. 8). Its dimensions (not including the spines on the edges of the periphery) are : — diameter 17 mm. ; width of umbilicus 4'5 mm. ; height of outer whorl 8 mm. ; greatest thickness (which is at a very short distance from the umbilicus) 4*5 mm. At the base of the body-chamber the height of the whorl is 5 mm., and its thickness 3"5 mm., the transverse section being sublanceolatc. Measured along the curve of the inner portion of the lateral area, the anterior boundary of the muscular attachment can be seen as much as G'5 mm. in advance of the last septum. After passing backward at a distance of 1'75 mm. from, and parallel to, the inner edge of the whorl for a distance of about 5 mm., the boundary then passes outwards in a shallow curve towards the pcrijihery, just before reaching which it turns slightly forward. There does not appear to be a definite line at the anterior extremity of the forward prolonga- tion of the impression, but the area included between the boundary of the muscular attachment and the inner edge of the whorl is a little roughened, the surface of the specimen outside this line being smooth and polished. Where the boundary turns outward there are several fine incised concentric lines. It is to be observed that the boundary of the forward prolongation of the muscular attachment does not coincide Avith the longitudinal groove running along the middle of the lateral area, but is situated between the inner margin of the whorl and this groove. ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 101 The smaller example (No. C. 51iO h), wliich exliibits the muscular attachment, has the following dimensions (excluding both the height of the peripheral spines and the inflated terminal portion of the body-chamber) : — diameter 15 mm. ; width of umbilicus 4 mm. ; height of outer whorl 6'5 ; thickness 1 mm., the whorl at the base of the body- chamber being 4'5 mm. high and 3 mm. thick. In this specimen the outer boundary of the forward ijrolongation of the muscular attachment is slightly more distinct than in the example already described, and appears to be continued backward as a dark (not incised) line into the second lateral lobe on one side of the specimen and on to the second lateral saddle on the opposite side, but txt about 2'5 mm. from the last septum it gives off a branch which curves outward towards the peripheiy, where it is bent slightly forward. The width of the forward prolongation of the impression is 1"5 mm., the most anterior part of the impression being 5 mm. from the last suture-line. The form and position of the muscular attachment in this species are also exhibited by a specimen * (No. 22267) in the British Museum from the Brown Jura ^, Beuren, Wiirtemberg ; it agrees with that already described in the example C. 5110 a. In this species, then, the shell-muscle seems to have been attached to the long flattened siu'face on the inner area of the body-chamber. The anterior border of the shell-muscle and of the annulus agrees almost precisely wdtli that described and figured by Oppel in his well-known figures of Ammonites \z:=^Oppelia\ steraspis from the Lithographic Stone of Solenhofen, Bavaria, a fact which supports Prof. Zittel's arrangement of the genera Distlchocerus and Oppella in the same subfamily [OppdirKc). S T E p H A N o c E R A T I D ^, Ncuuiayr, emend. Zittel. Stephanoceras, Waagen. 8tep}ianoceras BanJcsii, J. Sowerby, sp. — There are indications of the muscular attach- ment of the animal in Sowerby's type-specimen, which forms part of the British Museum Collection. It is a natural internal cast from the Inferior Oolite of the West of England, but the 2^recise locality is not recorded. Its diameter is about 230 mm. (about 9 inches) and its thickness about 150 mm. (or nearly six inches). One-third of the outer whorl is occupied by the body-chamber, the base of which is 50 mm. high and 130 mm. mde. The inner area of the whorl is convex and slopes considerably towards the umbilicus. On the inner area, and arising from the suture of the shell at a point 43 mm. in advance of the last sejjtum, there is a faint impressed line which jiasses backward and outward across the inner area, crossing the umbilical mai'gin at about 30 mm. posterior to its point of origin and 25 mm. from the suture of the shell. Arising from the suture of the shell, and at a point 20 mm. posterior to the line cxlready described, there is another groove which is rather more distinct and passes backward (more quickly than the anterior line) and outward for rather more than 10 mm., then, with a forwardly-concave curve, passes * A peculiaritj- about this specimcu is that the chambers are arranged as it were in pairs, a large loculus being succeeded by a small loculus. This is certainly the case with the last sixteen chambers. 102 ME. G. C. CEICK ON THE MUSCULAE ATTACHMENT OF THE to about the middle of tlie inner area, and then turning backward again it disappears in the broken surface of the specimen. The anterior line probably indicates the position of the anterior boundary of the shell-miiscle, and the posterior line possibly the posterior l)0undary of the same ; I think the latter cannot indicate the position of a former attachment of the anterior boundary, for it is not parallel to the anterior line. The other side of the specimen is too badly preserved to show the muscular impression. I have not observed any indications of the position of the annulus iu this specimen. Perisphikctes, Waagen. Ferisphinctea Achilles, d'Orbigny, sp. — The lateral aspect of the muscular impression in this sj)ecies is clearly shown in an example in the British Miiseum Collection (the smaller of the two specimens. No. 37017) from the "White Jura of Randen, near Schalfhausen (PI. 19, fig. 5). The example is a natural internal c;xst, almost completely denuded of the test. Its dimensions are : — diameter of shell 69 mm. ; width of umbilicus 28 mm. ; lieight of outer whorl 24*5 mm. ; greatest thickness (almost close to the umbilicus) 16 mm. The whorl is much compressed, and not much indented by the preceding whorl ; the body-chamber, measured along the median line of the periphery, is about 80 mm. long. The incised line marking the boundary of the muscular iuipression is j)lainly visible at the base of the body-chamber. At the inner edge of the whorl it is 5 '5 mm. in advance of the most anterior part of the last septum ; passing backward and out- ward for a short distance, it is then continued backward as an exceedingly faint line as far as the last septum in a direction nearly parallel to the inner edge of the whorl. The width of the im^u'cssion from the suture of the shell is 2'25 mm., of which only about one-half is visible in the lateral aspect of tiic shell. The boundary of the anterior portion of the scar is more deeply incised than the rest. The impression on the other side is similar, l)ut not qviite so distinct. There is no trace of the annulus. AsPIDOCEKATID^, Zittel. Peltoceras, Waagen. Peltoceras sp. — The impression of both shell-muscles is well seen on an example of Peltoceras sp. that was found in the Ampthill Clay at Ampthill Tunnel, and that formed part of my late father's collection (PL 20. fig. 1). The specimen, a mere fragment of the natural cast of a large shell, consists of the posterior part of the body-chamber ; it is about 150 mm. long. It is quadrangular in transverse section, and at the base of the body- chamber is 73 mm. high, 65 mm. thick (excludiug the ribs), and 72 mm. thick (including the ribs). An antiperipheral, autisiphoual, or dorsal aspect of the fragment disjilays two longitudinally-elongated oval scars, somewhat pointed anteriorly and bounded by a faintly impressed line. The outer boundary of each area terminates ioimediately above the inner branch of the lateral saddle, while the inner boundary passes down close to the outer side of the antij^eripheral (or autisiphoual) saddle on the same side. The anterior extremity ANIMAL TO ITS SHELL IN SOME EOSSIL CEPHALOPODA. 103 of each impression is situated on the edge of the impressed zone, so that about one- third of the width of the impression is on the impressed zone, the other two-thirds being on the inner area of the whorl. The two impressions are nearest together at about half their length ; they are here 19 mm. apart, while the posterior extremities of their inner boundaries are 32 mm. apart. The length of each impression (measured from the anterior extremity of the inner branch of the lateral saddle) is about 50 mm. ; the greatest width being 17 mm. No traces of the annulus have been observed in this specimen. In the middle of the peripheral area, and extending a short distance into the peripheral lobe, there is a broad, faint, longitudinal depression about 25 mm. long and 3'0 mm. wide, slightly wider anteriorly than posteriorly. Possibly this had something to do ^^'ith the muscular attachment of the animal to its shell. On one side of this there is a narrower, shorter, and less distinct longitudinal depression. AsPiDOCERAS, Zittel. Aspidoceras sp. — Among the si^ecimens which Dr. J. W. Gregory collected from " below Chamgamwe, opposite Mombasa Island," East Africa, there is a fragment of an Aspidoceras which displays the muscular impression ; it is merely the natural cast of the posterior part of the body-chamber, and this is incomplete on one side (PI. 19. iigs. 6, 7). The section of the base is obtusely cordate, and measures about 43 mm. in width and 34 mm. in height. The impression is seen on the inner area of the whorl as a faintly- impressed line, which, ai'ising from the edge of the impressed zone (corresponding to the suture of the shell) at a point about 15 mm. in advance of the base of the body-cliamber, passes outward, describing a curve slightly convex forward, and when at a distance of 9'5 mm. from the edge of the impressed zone jiasses backward nearly parallel to this edge for a distance of at least 10 mm. It then seems to divide into several very faint grooves which are continued backward nearly to the base of the body-chamber. No indications of the annulus can be seen. Unfortunately the cast is very imperfect on the opposite side. C O S M C E R A T I D .E, Zittel. Parkinsonia, Bayle. Parkmsonia Parkinsoni, J. Sowerby, sp. — The muscular impressions are well shown in a Avell-preserved example of this species in the British Museum Collection (No. 9) from the Inferior Oolite of Bayeux (Calvados), Prance. PuUy two-thirds of the outer whorl are occupied by the body-chamber ; the test having been removed from the greater part of this chamber, the internal cast is well displayed. The dimensions of the specimens are : — diameter of shell 213-5 mm. ; width of umbilicus 58 mm. ; height of outer whorl 49 mm. ; greatest thickness of ditto o2'5 mm. The body-chamber appears to be fairly complete ; its length measured along the median line of the periphery is 287 mm. ; and the dimensions of its base are : — height 31'5 ram., greatest thickness (which is at about one-third of the height of the whorl from the inner edge) 22-5 mm. The muscular impression on each side can be seen. At the suture of tlie shell the SECOXD SERIES. — ZOOLOGY, VOL. VII. 15 104 MR. G. C. CRICK ON THE MUSCULAR ATTACHMENT OF THE anterior border, an incised line, is 9'5 mm. in advance of that portion of the lateral saddle of the last suture-line which is close to the umbilical margin ; it passes thence outward and backward nearly parallel t6 the suture and almost as far back as the last septum, when it appears to turn ovitward and pass over this portion of the lateral saddle as a feebly-depressed rather than an incised line. This last-mentioned portion of the boundary may have been produced by the anterior border of the annulus. The greatest width of the portion of the impression that is visible is 5 mm., and it is confined to the somewhat sloping inner area of the whorl. Its surface is a little roughened, and the ira^^ression seems to have occupied the lol)e which is situated on the inner area of the whorl. An irregular, waved, depressed line passes over the siphonal lobe on eacli side of the body-chamber, and this most probably indicates the position of a further jDortion of the anterior border of the annulus. P R I o N o T R o P I D .E, Zittel. ScHLCENBACHiA, Neumayr. Schloenhachia GoodhalU, J. Sowerby, sp. — The remains of the muscular attachment are exhibited by an example of this species in the British Museum Collection (No. 46491). The specimen is from the Greensand of Blackdown, Dorset. It consists of a segment of two adjacent whorls, the outer of \\hich exhibits at about its mid-length the basal l^ortion of the body-chamber, which on the left side is entirely denuded of the test. The whorl is carinated, much compressed laterally, and its sides nearly parallel ; at the base of the body-chamber it is 80 mm. high and 45 mm. wide or thick, the inner area being concave, sloping towards the umbilicus, and 12 mm. wide. On the left side, on the internal cast of the body-chamber, the anterior boundary of the muscular scar is seen as an incised line arising at the suture of the shell at about 30 mm. in advance of the corresponding portion of the last septum ; passing obliquely backward and outward across the inner area, it crosses the umbilical margin at about 22 mm. in advance of the corresponding part of the last septum ; it continues outward and backward for a short distance, and then divides ; one part joasses backward and outward for a very short distance and then disapjiears ; the other passes backward nearly parallel to, and at a distance of 4 mm. from, the umbilical margin, and disappears shortly before reaching the suture-line of the last septum. The branch which passes outward is probably the com- mencement of the anterior border of the annulus, the other being the outer boundary of the muscular scar. Arising from the suture of the shell, 13 mm. posterior to the line already described, and crossing the inner area nearly parallel to the same line, there is another very feeble groove, which scarcely crosses the umbilical margin before reaching the last suture-line. Prom the appearance of the inner surface of the piece of the test which fits on to this portion of the specimen, it seems most probable that this feeble groove indicates the position of the posterior boundary of the muscular scar. The opposite side of the whorl is too imperfect to exhibit any trace of the muscular attachment. ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 105 At a point 29 mm. in advance of the small median saddle, the periphery is crossed by an incised line which on the left side passes inward and backward for about 8 mm., tlien passini? backward nearly parallel to, and at a distance of 8 mm., from the median line of the perijAery until it meets the external saddle. Traces of a precisely similar line can also be seen on the right side. This I believe to have also been part of tlie anterior boundary of the annulus. Clymenia., Miinster. CUjmeuia imdulata, Miinster. — The muscixlar impression in the genus Clymenia has been best observed in an example of this species in the British Museum Collection (No. 81826). It is from the Clymeuien-Kalk (Upper Devonian) of Scbiibelhammer, Bavaria (PI. 20. figs. 13, 14). This specimen, the outer wdiorl of which is somewhat imperfect, has the following dimensions : — Diameter of shell 48'5 mm. ; width of umbilicus 20'5 mm. ; height of outer whorllG mm. ; greatest thickness of ditto 12 mm. Nearly one half of the outer whorl is occupied by the body-chamber, its length, measured along the periphery, being 65 mm. ; its anterior portion is flattened for a distance of nearly 20 mm., the width of the flattened portion being 3 mm. It niay be remarked that in this genus the siphuncle is on the inner side of the whorl, and is relatively much larger than in the rest of the Ammonoidea. The internal cast of the posterior part of the body-chamber and of two or three of the succeeding loculi is denuded of the test. The base of the body- chamber is 12'5 mm. high and 10 mm. thick, the periphery here being quite rounded. One side of the basal portion is w^ell-preserved, but tlie other is somewhat imperfect. On the well-preserved side (fig. 13) a curved feebly-iucised line arises almost close to the suture of the shell and at a distance of 2 mm. from the last sejitum ; j)assing backward nearly parallel to the inner half of the lateral portion of the suture-line, it just clears the most anterior poi'tion of the latter and then passes straight on to the periphery, being at the centre of the latter about 2 mm. anterior to the last septum. It appears to cross the periphery without iuterruj)tion, but unfortunately the line here is somewhat obscured, and it is not impossible that the line here may be bent backward into a very minute V-shaped sinus. Another feebly-incised line proceeds from the suture of the shell and passes backward almost close to the last septum for some distance into the lateral lobe ; then turning forward it meets the anterior line, already described, at the most anterior point of the lateral portion of the suture-line. At a short distance from this junction and a little nearer the periphery, the anterior line gives off a bi-anch which gradually recedes from it and crosses the periphery about 1 mm. posterior to it. At the central portion of the periphery this line, like the anterior one, is somewhat obscured, but appears to cross the periphery without interruption, although it is not impossible that at the middle of the periphery this line may have had a very small V-shaped bend forward. It would seem, therefore, that the shell-muscle occupied the space between tlie suture of the shell and the outer side of the lateral lobe, and that the annulus extended from 15* 106 ME. G. 0. CEICK OX THE MUSCULAR ATTACHMENT OF THE tlie outer side of the lateral lobe across the perijihery as a narrow band having its greatest width at the centre of the periphery. Unfortunately, the opposite side of the body-chamber is not sufficiently well-preserved to show the muscular impression. Near the anterior end of the body-chamber the internal cast exhibits a wide and fairly deep groove, which crosses the lateral area in a curve which is concave forward, and projects considerably forward near the periphery. The lateral portion of the sroove is fully mm. wide, but shallow, while the portion near the periphery is 4 mm. wide and deeper than the rest. The opposite side of the specimen is broken here, and does not show the groove. This groove, however, seems to have nothing to do with the muscular attachment of the animal, but is here mentioned for comparison with tlie groove which has been depicted in some Ammonoids (e. g. Pinacoceras*) as the anterior bonndarv of the muscle and of the annulus. GONIATITES. Gltphioceeas, Hyatt. Glyphioceras crenistria, J. Phillips, sp. — Among the Goniatites the form of the attach- ment of the animal to its shell is well seen in an example t of this species from Bolland, Yorkshire (PL 20. figs. 15, 16). It forms part of the British Museum Collection (No. C. 5080). It is a Avell-preserved example, having the following dimensions: — Diameter of shell 43 mm. ; width of umbilicus about 4*5 mm. ; height of outer whorl 21-5 mm.; thickness of ditto 27'5 mm. The body-chamber occupies five-sixths of the outer whorl, and, being denuded of the test, its internal cast is well displayed. The muscular attachment is so well preserved that it can be traced from the umbilicus on one side across the whorl to the umbilicus on the other side. As seen in a lateral aspect (fio". 15) the muscular scar is almost confined to the inner area of the whorl, and is depressed (on the internal cast) a little below the sui'rounding surface. The most anterior portion of its anterior boundary is a little more than 2 mm. in advance of the last septum. Passing backward and outward, this boundary just crosses the umbilical margin and reaches to within about 1 mm. of the septum, when, turning abruptly outward, it is continued as a very fine raised line at this distance from the septum, until passing into the lateral lobe, when it recedes very slightly from the suture-line. It crosses the lobe in an obtuse point 3"75 mm. from the point of the lobe, and, then passing up the other side of the lobe, it gradually approaches the suture-line and, just clearing the pointed external saddle, passes into the external lobe at about 1 mm. from the septum (fig. 16), at the same time separating into two very minutely -waved lines; at 5 mm. from the apex * Dr. E. V. Mojsisovics, ' Das Gebirge um Hallstatt," i. pi. xx. figs. 2 & 3 (^Pinacoceras insectum) ; pi. xx. figs. 8 & 9 {P. liumilc). t This is the specimen from which the suture-liue figured in Cat. Eoss. Ceph. British Museum, pt. iii. p. 101, fig. 76, was drawu. ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 107 of the external saddle these lines diverg-e, assume a direction at right angles to the plane of symmetry of the shell, and cross the external lohe with only a very sliglit V-shaped depression at the median line of the periphery. jS'early at the centre of the peripliery there is a small circular pit on the posterior lino. On the opposite side of the lobe, at about 1 mm. from the suture-line, these lines turn aliruptly forward, approach and coalesce, the resulting line having the same course as that on the opposite side. At the umbilical margin this line passes into the boundary of the muscular scar, which also has the same form as that on the opposite side. At the centre of the periphery and imme- diately behind the lines already described there is a feebly-depressed double line in the form of a horse-shoe, each side of which passes quite close to the outer side of each half of the small median saddle; the enclosed area is about 2 mm. wide. At a short distance anterior to the raised line already described there is a rather broad shallow groove, which first makes its appearance in the lateral lobe, becomes more distinct all around the external saddle, and disappears in the external lobe. Almost in the median line of the periphery, and slightly in advance of the apex of the external saddle, there is a minute, shallow, oval depression. A fairly-jirominent " normal line " extends some 7 or 8 mm. in advance of this depression, whilst the surface of the cast behind this depression and in front of the anterior boundary of the annulus bears numerous fine longitudinal raised lines. The depressed surface on the inner area of the whorl I regard as a portion of the muscular scar, and the faint line proceeding therefrom across the whorl I consider to be the impression of the annulus. The latter then seems to have been over a portion of its extent merely a line of attachment, but to have been 1 mm. wide on the periphery. In the present specimen the boundary of the muscular scar cannot be traced on to the inner or dorsal poi'tion ( = impressed area) of the whorl, Init this has lieen partially observed in another example of the same species in the British Museum Collection (the larger of the specimens Xo. C. 283). The diameter of the shell is 50 mm., the outer whorl (at the end of the septate part of the shell) being about one-half of the diameter. The specimen is entirely septate (PL 20. figs. 17, 18), tlie last septum being the base of the body-chamber. A portion of the test that formed the floor of the body-chamber still adheres to the preceding Avhorl, and on this the border of the muscular scar can be traced for a short distance. In this example the anterior border of the scar j^asses on to the floor of the body-chamber at about 3"5 mm. in advance of the last sej)tum ; for a short distance it is nearly parallel to the sejjtum, Imt at about the middle of the lateral saddle it turns towards the septum and seems to disapjiear ; unfortunately the test here has been broken away, and only a few fragments of the test remain on the opposite side of the whorl, so that its direction cannot be definitely traced further. On the floor of the body-chamber (fig. 18) there is also a strong raised line following the lobes and saddles of the last septum, and about 1 mm. in front of the same ; near the umbilicus it gradually approaches and then passes into the angle between the septum and the wall of the shell. This seems to have been a line of attachment of the body of the animal ; but, so far as can be made out from this example, it does not ajipear to have been continuous 108 MR. G. C. CRICK ON THE MUSCULAR ATTACHMENT OF THE with tlie anterior border of tlie muscular scar. It may have been the line of attachment of the j)osterior 2iortion of the body just prior to the formation of a new septum. Glypliioceras trimcatum, J. Phillij^s, sp. — An example of this species from the Carboniferous Limestone of St. Doulagh's, co. Kildare, Ireland, which has been lent me by Dr. A. H. Poord, T.G.S., also exhibits the anterior boundary of one of the muscular scars A^ery distinctly (PI. 20. figs. 19). The specimen consists of about five-sixths of a whorl, the whole constituting- part of the body-chamber, the base of which is fortunately preserved. Its dimensions are: — diameter 75 mm.; height of outer whorl 36 mm. ; ditto above jireceding Avhorl 20 mm. ; greatest thickness (which is at about the middle of the lateral area) 27 mm. ; width of umbilicus 10 mm. On one side of the specimen the anterior boundary of one of the muscular scars is preserved as an impressed line (on the internal cast of the body-chamber), which arises from tlie suture of the shell at about 4 mm. in advance of the last septum and curves gently outward and backward. It can only be traced for a length of about 6 mm., when it is obscured by the test ; at about one-half of this lencrth it is 45 mm. from tlie suture of the shell. Summary. As in the recent Nautilus, so in the Ammonoids, the shell was external and the animal was attached to its shell by means of " shell-muscles " and an " annulus." In the Ammonites and such allied forms as BacuUtes, Samites, &c. the shell- muscles Avere attached to the dorsal portion of the shell; they frequently either approximated or met each other in the median line of this region ; when they did not quite meet they Avere doubtless united by a more or less narrow band corresponding to the dorsal portion of the annulus in the recent Nautilus. My observations support the conclusion expressed by Dr. Waagcn that the line figured by Oppel on the body-chamber of Ammonites steraspis indicated the position of the anterior boundary of the annulus and of the shell-muscles, the latter being situated, as he supposed, upon the inner or umbilical portion of the lateral area of the AA^iorl. It is, howcAer, not a little sti*ange that in the species figured by Oppel the form of the muscular attachment differs somcAvhat considerably from that in the majority of the Ammonites which I have examined. It would seem that another intei'pretation is necessary for the figures Avhich have subsequently been given purporting to be the remains of the muscular attachment. In the earlier stages of develoj)ment and in the general form of the shell as well as in the aperture of certain species, affinities have been recognized betAA^een the Ammonoids and the Dibrauchiatcs. Prom the foregoing it is clear that the Ammonoid animal possessed a muscular attachment quite similar to that of the living Nautilus, the only recent genus of the Tetrabranchiates. Indications of the muscular attachment of the Ammonoid animal, instead of being rare, seem to be fairly common. There appears to be some ground for believing that its form is in j^art due to the shape of the transverse section of the Avhorl and to the ajN'imal to its shell in some fossil cephalopoda. 109 length of the hody-chamher, hut I venture to helieve that it will prove to ha clue to other causes, and also affoi'd an important character for the purposes of classification. Thus, among the forms of muscular attachment descrihcd in the present paper, the shell-muscles in Distichoceras and Oi^peUa seem to have been relatively much longer than those of the other forms herein described ; and hence one should expect these two genera to be closely related. Tliis affinity seems to be supported by their other characters, for they have been placed in the same subfamily, viz. the Oppelince*. Not only was the Ammonoid animal, like the Nautilus, at least at some periods, attached to its shell by means of the lobes and saddles of the posterior portion of the body (corresponding to those of the edge of the septum of its shell), but it seems from the foregoing descriptions that it was further provided with an annulus in addition to shell-muscles as in the recent Naiitilus. It would appear, therefore, as if the provision of an annulus were an absolute necessity to the animal in addition to the shell-muscles, and most probably Dr. Waagen's explanation of its occurrence is the correct one, viz., that the annulus and shell-muscles served not merely to hold the animal to its shell, but formed also an air-tight band around it, fastening the mantle to the shell. In conclusion, I desire to express my obligations to those who have in any way assisted me in my observations. To Dr. Woodward I am greatly indebted for valuable suggestions and much kind help, while to Mr. B. B. Woodward I am especially indebted for the advice which he has ever been most willing to give me. My thanks are also due to my colleague Mr. Edgar A. Smith for giving me every facility in the examination of the recent Cephalopoda under his charge. For the loan of specimens I have to thank Mr. F. L. Bradley, Mr. G. P. Harris, and the authorities of the Jermyn Street Museum. To Messrs. Sharman, Newton, and Allen, of that Museum, I am under deep obligations for all their kind help during the examination of the specimens under their charge. To Professor Howes, whose interest in my work has been a source of great encouragement to me, I desire to present my cordial thanks. EXPLANATION OF THE PLATES. The figures are of the natural size unless otherwise stated. X indicates tlie last septum. — * marks the remains of the muscular attachment. Plate 17. Baculites ovatus, Say (p. 77). Fig. 1. Dorsal aspect of fragment of body-chamber, showing anterior boundaries of muscular scars. 2. Right lateral aspect of same, showing on the left the boundary of the right muscular scar, and on the right the incised line on the ventral area. See Prof. Dr. K. A. v. Zittel, ' Grundziige der Palaoutologie,' p. 420. 110 ME. G. C. CEICK ON THE MUSCULAE ATTACHMENT OF THE Fig. 3. Ventral aspect of same, showing incised line on median portion. 4. Right lateral aspect of fragment of another example, showing anterior bonndary of right muscular scar and of a portion of the anuulus. Baculites vagina, Forbes (p. 78) . Fig. 5. Dorsal aspect of portion of body-chamber, showing near the base the anterior boundary of the two muscular scars. Hamites maxinms, J. Sowerby (p. 79). Fig. 6. Dorsal aspect of body-chamber, showing the two muscular scars near the base. 7. Left lateral aspect of the same. 8. Dorsal aspect of another example. 9. A portion of the same enlarged, showing the two scars, each bearing near its anterior border a small roughened patch, and also traces of a narrow band connecting the scars. X '{. Cr'wceras quadratum, n. sp. (pp. 74 & 79). Fig. 10. Dorsal aspect of a fragment of the body-chamber, exhibiting the two scars. 11. Left lateral aspect of the same. 12. Dorsal aspect of a frajjment of another example in which the anterior boundaries of the two scars nearly meet in the median line. 13. Left lateral aspect of the same. Ancyloceras Matheron'ianmii, d'Orbigny (p. 80). Fio-. 14. Left lateral aspect, showing portion of anterior boundary of left muscular scar, x \. 15. Right lateral aspect of a portion of the same, exhibiting the termination of the anterior boundary of the right muscular scar. X 5. If). Dorsal aspect of a portion of the same, showing the anterior boundaries of the two muscular scars, that on the riglit being much higher than that on the left. X \. Macroscaphites giyas, J. de C. Sowerby, sp. (p. 81). Fig. 17. Riglit lateral aspect. x\. 18. Left lateral aspect of a portion of the same, showing part of the boundary of the two scars. X 5. 19. Dorsal aspect of a portion of the same, also showing the anterior boundary of the two scars. X 5. Scaphites binodusiis, A. Roemer (p. 81). Fig. 20. Left lateral aspect. 21. Dorsal aspect of a portion of the same, with part of the body-chamber removed. Scaphites aqualis, J. Sowerby (p. 82). Fi"'. 22. Dorsal aspect of a fragment of the body-chamber. The curved lines at the lower part of tlie figure are the impressions of the ornaments of the septate part of the shell ; the anterior border of the muscular attachment is indicated by the arrow. ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. Ill Plate 18. TurrUites tuberculatus, Bosc (p. 83). Fig. 1. Lateral aspect, two of the upper wliorls exhibiting the siphuncle {si), and tlic body-cliamber showing the muscular attachment, x ^. 2. Dorsal aspect of body-chamber of same, showing the muscular attachment. X \. TurrUites Mantelli, Sharpe (p. 83). Fig. 3. Lateral aspect of fragment, the lower whorl of which exhibits a portion of the boundary of the muscular attachment. x |. TurrUites {Heteroceras) polyplocus, Roemer (p. 84) . Fig. 4. Lateral aspect of terminal portion. X |. Oxynoticeras ? sp. (p. 85) . Fig. 5. Left lateral aspect of part of an example showing the muscular scar and the annulus. x 5. 0. Right lateral aspect of same, x f . Amaltheus spinatus, Bruguiere, sp. (p. 86). Fig. 7. Left lateral aspect of imperfect specimen, exhibiting on the inner portion of the whorl (opposite the arrow) the boundary of the muscular scar. Cardioceras excavutum, J. Sowerby, sp. (pp. 75 & 86). Fig. 8. Left lateral aspect, showing the muscular scar and the annulus. x h. Cardioceras aff. excavuto, J. Sowerby, sp. (p. 80). Fig. 9. Left lateral aspect, exhibiting the ar.tcrior boundary of the muscular scar on the inner portion of the whorl opposite the aiTow, and a linguiform impression on the middle of the lateral area. 10. Dorsal aspect of posterior portion of the body-chamber of the same, showing near the base the course of the anterior boundary of the muscular scar on the dorsal area of the whorl. Tissotia EwahU, v. Buch, sp. (p. 90). Fig. 11. Left lateral aspect, showing close to the umbilicus (opposite the arrow) one of the muscular scars, and, passing from it towaids the peripheiy, a portion of the anterior boundary of the annulus. x f . Plate 19. Cardioceras excaratnm, J. Sowerby, sp. (p. 86). Fig. ] . Right lateral aspect, x §. 2. Sagittal section of the natural internal cast of the body-chamber of the same specimen, showing anterior boundary of muscular scar on dorsal portion of whorl. X f . Cardioceras sp. (p. 89). Fig. 3. Left lateral aspect, showing anterior boundary of scar and of annulus. x 'j. 4. Ventral view of the same, exhibiting the impression on the central portion of that area. SECOND SERIES — ZOOLOGY. VOL. YII. 10 112 MR. G. C. CRICK ON THE MUSCULAR ATTACHMENT OF THE Perisphinctes Achilles, d'Orbigny, sp. (p. 102). Fig. 5. Left lateral aspect. The boundary of the muscular scar is seen on the inner portion of the outer whorl opposite the small arrow. Aspidoceras .«/*. (p. 103). Fig. 6. Dorsal aspect of a fragment of the body-chamber. 7. Right lateral aspect of the same. Arietites obtusus, J. Sowerby, sp. (p. 93). Fig. 8. Left lateral aspect of a portion of a specimen, showing the muscular scar on the inner portion of the outer whorl opposite the arrow. 9. Right lateral aspect of the same. 10. Ventral aspect of the same, showing the liuguiform impression on the central portion, and anterior to it an /-shaped incised line in the depression on each side of the keel. Lytoceras fimbriatum, J. Sowerby, sp. (p. 91). Fig. 11. Dorsal aspect of the posterior portion of the body-chamber, exhibiting the left and a portion of the right muscular scar. 12. Left lateral aspect of the same. Lytoceras cornucopite, Young & Bird, sp. (p. 91). Fig. 13. Dorsal aspect of the posterior portion of the body-chamber. 14. Right lateral aspect of the same. 15. Right lateral aspect of another specimen, showing the small oval scar on the inner part of the outer whorl opposite the aiTOw. 16. Portion of same enlarged, showing muscular scar. X f . 17. Ventral aspect of portion of same enlarged, exhibiting the linguiform impression, x "f . Plate 20. Peltoceras sp. (p. 102). Fig. 1. Dorsal aspect of fragment, showing the two elongated muscular scars. X ^. ^goceras capricorimm, Schloth., sp. (p. 95). Fig. 2. Right lateral aspect. The muscular scar is the small white patch on the inner portion of the outer whorl opposite the arrow. j^goceras laqueolum, Schloenbach, sp. (p. 96). Fig. 3. Dorsal aspect of fragment of body-chamber, showing the left muscular scar and part of the right. 4. Left lateral aspect of the same. ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 113 Hecticoceras hecticuni, Reinecke, sp. (p. 98). Fig. 5. Left lateral aspect, x if . 6. Right lateral aspect of same. x %. 7. Ventral aspect of portion of same. X i'. Distichoceras Baiigieri, d'Orbiguy, sp. (p. 100). Fig. 8. Right lateral aspect, x j. CEcotraustes crenatus, Bruguiere, sp. (p. 99). Fig. 9. Right lateral aspect. X f. Arietites raricostatus , Zieten, sp. (p. 94). Fig. 10. Left lateral aspect of entire specimen. 11. Dorsal aspect of the portion ab, which is a natural internal cast of part of the body-chamber showing at the base the remains of the two muscular scars. Sonn'uiia sp. (p. 98) . Fig. 12. Left lateral aspect, exhibiting the muscular scar on the inner portion of the outer whorl opposite the arrow, and also the adjacent indentations. Clymenia undulata, Miinster (p. 105.) Fig. 13. Right lateral aspect. 14. Peripheral aspect of the same. Glyphioceras crenistria, J. Phillips, sp. (p. lOG). Fig. 15. Left lateral aspect. The fine white line opposite the arrow is the boundary of the annulus ; the subtriangular patch into which it passes near the umbilicus is the left muscular sear, the black line posterior to it is the edge of the last septum, the lighter portion near it being the broken edge of the test. 16. Front view of the same, the arrow pointing to the line indicating the annulus. 17. Left lateral aspect of another example. The anterior septum is the base of the body-chamber. The muscular scar is indicated by the light patch (opposite the arrow) on the piece of the test, one layer of which is part of the floor of the body-chamber. 18. View of same from above ; the raised line on the piece of test wliicli is part of the floor of the body-chamber being indicated by the white line marked a. Glyphioceras tnmcatum, J. Phillips, sp. (p. 108). Fig. 19. Left lateral aspect. X j. Crick. TrAKS.LiNN .Soc . ZoOL .SER.2.VoL,.Vn .PI .17. z'^"'^'*^, -^ r^i;?:sf"^"'1 ?i"? «\rf ^.^/r^fWi '"t*),,.-. I' J .-& PL -.- f (A frt r ') \^ l '^1 ^^ »-4^ c ^ '^*-l ^~^^^/ -=''<«lii:4^ •*- -aa^iij^ J Green, del etlitb.. -. V rr::^?;^,. — ^ j_ — — ^tt ^ — ^isSi ManternBros irtLp . MUSCULAR IMPRESSIONS IN FOSSIL CEPHALOPODA. Cricls. . Trans .Linn Soc Zool . Ser.2 .Vol .VII, PI .13. i > //> 4P?>- J Greeiv del et litlr\ . MUSCULAP. IMPRESSIONS IN FOSSIL CEPHALOPODA MirLterruBros irap. Crick. Tr-Ans Likn Soc . ZooL . Ser . 2 .Vol, VII. PI . 20 . J Green del etlith IvIiTLterrL Bros nVp ■ MUSCULAR IMPRESSIONS IIJ FOSSIL CEPHALOPODA. LINNEAN SOCIETY OF LONDON. MEMORANDA CONCERNING TRANSACTIONS. The First Series of the Transactions, containing both Botanical and Zoological contributions, has been completed in 30 Vols., and a few entire sets are still for sale. Only certain single volumes, or parts to complete sets, may be obtained at the original prices. 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Part VI. 1896 8 Part VII. 1896. . . . 12 . . . . PartVIII. 1897 2 6 . . . . VII. Part I. 1896 10 Part II. 1897 12 . . . . Part III. 1897 6 . . . . Part IV. 1898 10 . . . . Price to Fellows. d. 6 4 6 18 1 1 12 9 3 9 1 9 4 6 9 4 6 6 9 1 1 2 1 10 1 3 3 7 6 18 7 6 6 9 2 7 6 9 4 6 7 6 2nd Ser. ZOOLOGY.] [VOL. VII. PART 5. THE ^y/ / 9 TRANSACTIONS OF THE LINNEAN SOCIETY OF LONDON. OBSERVATIONS ON THE STRUCTURE AND MORPHOLOGY OF THE CRANIAL NERVES AND LATERAL SENSE ORGANS OF FISHES; WITH SPECIAL REFERENCE TO THE GENUS GADUS. BY FllANK J. COLE, DEMON.STRATOn OF ZOOLOGY, UNIVERSITY COLLEGE, LIVERPOOL. {Comviunicnied by Pro^. W. A. Herdman, D.Sc, F.Il.S.) LONDON: PRINTED FOR TRE LINNEAN SOCIETY BY TAVLOli AND FRANCIS. RED LION COURT, FLEET STREET. SOLD AT THE SOCIETY'S APARTMENTS, BURLINGTON-HOUSB, PICCADILLY. W., AND BY LONGMANS, GREEN, AND CO., PATERNOSTER-ROW. ''■■' Ontoh(^r 1898. [ 115 ] V. Observations on the St7'nctiire and Moiyhology of the Cranial Nerves and Lateral Sense Organs of Fishes ; tcith special reference to the Genus Gadiis. By Frank J, CoIj'e, Demonstrator of Zoology, University College, Liverpool. [Communicated by Prof. W. A. Herdman, D.Sc, F.B.S.) AUG 20 >899 (Plates 21-23.) Read 3rd March, 1898. Contents. Page A. Introduction 116 B. Historical 117 C. Sensory Canals in General 120 Conclusions 120 D. Sensory Canals of Gadus morrhtia 122 (1) Supra-orbital Canal 122 (2) Lifra-orbital Canal 123 (3) Hyomandibular Canal 126 (4) Lateralis Canal 127 Supra-temporal Portion 127 Lateral or Body Portion 127 E. Gadus morrlMa and Gadiis virens compared . . 129 F. The Sense Organs on the Lateral line Canals . . 129 G. Other Sense Organs belonging to the Lateral line System 131 H. Eelation of the Sensory Canals to the SkuU . . 131 Conclusions 132 I. The Trigemino-facial Ganglionic Complex .... 133 J. Morphology of the Facial Ganglion 136 (1) Conclusions 142 (2) Typical Branchial Nerve 144 (3) Facial Nerve of Man 144 K. Morphology of Jacobson's Anastomosis 145 Conclusions 147 L. Metamerism of the Lateral line System .... 148 (1 ) Conclusions 152 (2) Value of the Lateral line Nerves 154 M. Innervation of the Sensory Canals in Gadus . . 156 (1) Supra-orbital Canal 156 Superficial Ophthalmic Trunk 156 SECOND SERIES. — ZOOLOGY, VOL. VII. Page (2) Infra-orbital Canal 158 Buccal Trunk 158 (3) Hyomandibular Canal 161 Hj'omandibular Trunk 161 (4) Lateralis Canal 164 Laterahs Trunk 164 N. Structure and Morphology of the R. lateralis accessorius (" trigemini '") 166 (1) Condition in Gadus 17.5 (2) General Conclusions 177 0. Morphological Value of the Lateralis Nerve of Petromyzon . 178 Conclusions 179 P. Gadus compared with other forms 179 Amia 181 Q. The Lateral Sense Organs of Vertebrates and Invertebrates 185 Conclusions 186 Iv. The Phylogeuy of the Sensory Canals 187 Conclusions 192 S. The Lateral Sense Organs and the Auditory Organ 194 Conclusions 197 T. Special Considerations 199 (1) Friant (1879) 199 (2) Morphology of the Facial Nerve of Fishes 200 Summary 203 Bibliography 20U 17 116 MB. F. J. COLE ON THE STRUCTURE AND MORPHOLOGY OF A. Introduction. 1 HIS investigation was first suggested to me as a desirable study by my former teacher, Professor J. C. Ewart, F.R.S., some years ago. I had at the time contemplated worknig at a Pleuronectid fish^ — allured by the problems which the asymmetrical head affords ; but it was pointed out that I should be better equipped for such difficult work were I to study a modern symmetrical Teleostean first, and that in fact it were almost an impossi- bility to understand the former without having first investigated the latter. I therefore abandoned my first project, and decided to work out the anatomy of the lateral line system and its nerves on the common Codfish. That this work was necessary, and indeed essential to the proper understanding of this complicated system, is very obvious from a perusal of the literature. In spite of the enormous bulk of the latter, and the ponderous theses and memoirs tlmt have been written on the subject of the present communication, we still know very little about the fine anatomy of the lateral line system, and very few authors have taken the trouble to grapple with the literature and to conduct their investigations on a strictly logical and scientific basis. To Mr. Edward Phelps Allis, who must be regarded as the pioneer in this work, vertebrate morphology owes much. He was not only the first to make a comjilete study of the topographical development of the lateral canals, and to give a correct and detailed account of their innervation, but many important morphological deductions have been directly inspii-ed by his work. This author has recently completed his work on Jmia. It is a completion upon which I may be permitted to cordially congratulate the author, and to express the hope that he will continue on other forms the studies he has pvn-sued with such conspicuous success on Amia. Ewart has followed Allis with an account of his skilled dissections of the very complex lateral line system of Lcemargus and Rata, and Pollard has added some details on the ancient Siluroid Teleosteans. Pinkus has very largely filled in a gap by an able account of the nerves of Protoptertis, and the writer has published a description of the system in Chimcera. The most pressing want, therefore, was an investigation of the details in a modern specialised Teleostean, and the pi-esent memoir is largely an attempt to supply this deficiency in our knowledge of this interesting apparatus in Gadus. The experience gained whilst working under Professor Ewart, and afterwards in investigating Chimcera, has been most valuable in the interpretation of the nerves of the Codfish. That the skeleton of this creature represents a very specialised condition is a palaeontological fact, and it is hence not surprising to find its nerves in an equally advanced stage. My previous work on the simpler cartilaginous fishes (most of which has yet to be published) has prevented me from going astray in the interpretation of the nerves, and has enabled me to see in the specialised Cod the disguised form of the primitive cartilaginous fish. The separation of the components in the Cod has necessarily been effected with the microscope, and one cannot urge too strongly the importance of this instrument in the elucidation of cranial nerve morphology. Investigations based solely on microscopic or naked-eye anatomy olten contain gross but pardonable errors ; and whilst, on the other hand, a combination of the two methods docs not indeed remove THE CRAISIAL NERVES AND LATERAL SENSE ORGANS OF FISHES. 117 the possibility of error, it certainly reduces mistakes to within a somewhat reasonable limit. Had I relied entirely upon sections, I should (as Pollard actually did) have described the lateralis accessorius as a modified lateral line nerve ; whilst, had I confined myself to naked-eye dissection, the very interesting condition of the " facial ganglion" would have entirely escaped observation. Pigure 1 (PL 21) and the description of the sensory canals themselves (pp. 122-129) are based on the dissection of a single specimen, which, as shown in the Plate, had its anterior and posterior narial openings abnormally fused together. The right side, how- ever, was normal in this respect. This specimen measured 237 mm. from tlie snout to the anterior extremity of the dorsal tin *, 210 mm. from the snout to the dorsal attacliment of the opercular fold, and 80 mm. from the barbel to the apex of the mid-ventral ano'le formed by the fusion of the two opercular folds. Its girth from the anterior extremity of the dorsal fin to the dorsal border of the base of the pelvic fin was 195 mm. The young Gadus vire/is used in the microscopic part of the work were obtained at St. Andrews, where, on this as on many other occasions. Professor W. C. Mcintosh, P. U.S., very kindly placed a table in his admirable new laboratory at my disposal. I also have to thank him for collecting the material and keeping it alive in the tanks when the exigencies of teaching left little time at my disposal. The smallest specimen I brought away from St. Andrews was 35 mm. long, but those sectioned were larger than that. They may therefore be described as young adults. To Professor G. B. Howes, P.Pt.S., I am indebted for much kindly assistance and encouragement, and indeed both to him and to my valued chief. Professor W. A. Herdman, F.R.S., I owe " many acts of kindness that I can never repay, and have no wish to, for I prefer continuing the obligation." The preparation of the bibliography, of which a section is printed at the end of this paper, and which will be published separately wdien completed, has necessarily laid me under obligations to many librarians, as well as to Professor Howes. Of these I should like to mention Mr. A. W. KajJiiel, of the Linnean Society ; Mr. P. H. Waterhouse, of the Zoological Society ; Mr. A. H. White, of the Ptoyal Society; and Mr. B. B. Woodward, of the Natural History Museum. To these gentlemen, who freely placed their knowledge and time at my disposal, I must express my heartiest thanks, B. Historical (G^i-f^s) t- The first reference I find to the sensory canals and cranial nerves of the Cod is contained in the work of Monro (144) published in 1785. Monro considered the lateral canals glandular oi'gans (i. e. " mucous canals "), and gives a large but superficial figure of Gadus in plate v., which shows the supra-orbital commissure and the median unpaired tubule, but which overlooks the supra-temporal canal. This author was the * The point of extension forward of the dorsal fin is extremely variable even in the same species, as may readily be seen by comparing common Cod placed side by side in a fishmonger's shop. t I purposely omit references to text-books that are in constant use, such as T. J. Parker's ' Zootomy,' &c. [Since this section was written, several other Oadus references have been encountered, but these will be fully treated in my complete Bibliography.] 17* 118 MR. F, J. COLE ON THE STRUCTURE AND MORPHOLOGY OF first to discover the nerve-supply of Lorenzini's ampuUse in Selachians. In 1825 Desmoulins and Magendie (60) gave a figure of the brain and roots of the nerves of the Cod, whilst Giltay in 183i (88) figured and described the sympathetic nervous system, of wliich more presently. Leuret and Gratiolet, in a fine work (1839-1857, 119) treat of some Invertebrate nervous systems, and give a brief account of the central nervous system and cranial nerve roots of a few fishes, including the Cod, as also does Alcock (3, 1839). In 1842 Stannius (198) commenced his studies on the peripheral nervous system, and published a careful description of the nerves of "■ Gudus callarias" {=G. mor/'hua). The results obtained on this form were included in his well-known general treatise published in 1849, which will be discussed elsewhere. In the same year he wrote a short note on the lateral canals of fishes (197), in which he briefly but accurately describes the lateral canals of " Gadus callarias^ He corrects Monro's mistake re tlie supra-temporal canal, and devotes a few lines to the nerve-supply, remarking that the supra-temporal lateral line nerve is homologous with the Ramus auricula ris vagi of higher Vertebrates. This homology can, of course, be maintained no longer. Bonsdorff', in 1846 (30), gives us one of an admirable series of papers on cranial nerves, and treats of the trigeminus and cephalic sympathetic of " Gadus lota " [=Lota vulgaris). He gives a good figure of the brain and nerves, but in his interpretation of the latter was greatly misled by comparing them in too much detail with the Mammalian nervous system. Stannius's monograph (1849, 199) is concerned largely with Gadus, and will be discussed further in the text. Besides giving a fine figure of the lateralis accessorius, and showing further its connection with the spinal nerves (in " Gadus callarias "), he gives a further figure of the cephalic sympathetic and arteries in the same animal. Leydig (1850, 120) was the first to describe the histology of the lateral sense organs in Lota vulgaris, and shoAvs the lateral line ossicle with its sense organ and perforating nerve. In Swan's beautiful atlas (1804, 205) there are several good figures of our type, but tlie accompanying text is unfortunately very meagre. The figure of the Cod's brain and nerves here given has been copied into several text-books, and may be seen in the first volume of Owen's 'Vertebrates,' p. 298. In Traquair's work on the asymmetry of the Pleuroneotidse (1865, 207), the first accurate account of the topography of the sensory canals of Gadus and their relations to the bones of the skull is given. A figure (tab. 32. fig. 1) is published indicating the approximate position of the various canals (omitting details), and Dr. Traquair puts to brilliant use the lateral line system in sustaining his views on the Pleuronectid skull, Owen (1866, 149) makes some references to the nerves of the Cod, but his statements and figures are compiled from the works of Swan, Alcock, and Cuvier and Valenciennes. The histology of the brain of " Gadus lota " has been treated of by Stied;i (1868, 201), who examined tiie nerve-tracts in the brain and spinal cord, and devotes a few notes to the roots of the nerves. A very important work, historically, which has hitherto been overlooked, and to whicii I shall refer in some detail later on, was published in 1879 by A. Friaat (73). This author describes and figures the brain and nerves of many bony fishes, including THE CRANIAL NERVES AND LATERAL SENSE ORGANS OF EISHES. 119 " Oadus carbonarius'' {=G. vlrens) (pi. v.) and " Gadus lota" (pi. vi.), and his work is remarkably accurate for the time it was published, anf'^ must certainly be regarded as a pioneer research. Cunningham (1890, 55) says (p. 77) : "In the Cod, which may be taken as exhibiting pretty nearly tlie original condition of the cephalic tubes of the Sole and other tlat flshes, tliere are no superficial sense-organs on the head, and the tubes of the two sides are symmetrically arranged." Omitting the last, I cannot acquiesce to any of these statements. The lateral sense organs have xicdoubtedly advanced purl passu A\ith the development of the skull and the evolution of the asymmetry of the Pleuro- nectidge. Cunningham's figure of the sensory canals of the Cod is copied " with slight modifications " from the figure given by Traquair in his Pleuronectid paper. Traquair's figure, as far as it goes, is perfectly accurate, and I must confess that Cunningham's modifications are somewhat unfortunate — especially the one that connects the liyo- mandibular with the lateralis canal. Further, the statement as to the absence of superficial sense organs is a curious oversiglit, especially as the mandilnxlar line of pit oi'gans is more obvious than these organs are in any other fish I am acquainted with. Allis, in his last Amia paper (1S97, 6), makes some passing references to Gadus, which he states are based on work being done in his laboratory by Dr. Dewitz and Mr. Samuel Mathers. On p. 631 he says : — " In Gadus there is a line of surface organs on the outer surface of the opercular bones immediately behind the preoperculum. They are all innervated by a special branch of the mandibularis externus facialis, and are therefore of the character of pit organs, and unquestionably represent in Gadus one of the cheek- lines of Amia or a similar line not found in Amia." Again, on pp. 032-633: — '' h\ Gadus a line of surface organs is found along the lower edge of the mandible, parallel to the mandibular canal, and it is innervated by a long branch of the externus facialis, which first runs forward through the adductor mandibuUe, to tlie hind edge of tiie infraorbital canal behind the eye, and there turns downwards and reaches the mandible. A nerve in Esox corresponding in position to this nerve in Gad/is innervates a line of surface organs lying on the upper jaw immediately below the infraorbital canal." Respecting the innervation of the latter organs lie says (p. 637) : — " Tiiis nerve [/. e. a branch of the externus facialis] in Silurus may l)e a l)ranch cori-esponding to the one which in Amia innervates the mandibular line of pit organs, and in Gadus innervates a mandibular line of the slit like organs peculiar to that fish." Finally Goronowitsch (1897, 90) has given an admirable account of the trigemino- facial complex of JLoia vulgaris, in which tlie histology of the medulla and the nerve tracts of the ganglionic complex are ably elucidated and described. It is thus seen that our knowledge of the lateral sense organs and their associated nerves in Gadus is still of a vei'y imperfect description, and in fact all the work of any pretension was done before the lateral line system w'as properly understood, and l)efoie the researches of Allis, Ewart, and Strong had placed our knowledge of this interesting- system on a secure basis of carefully ascertained fact and logical deduction. It is the purpose of the present communication to supply this defect, to add some new facts 10 our knowledge of the lateral organs, and jJerhaps to elucidate many points that are still somewhat obscure. I find with Allis that " as the work has j)rogressed it has repeatedly 120 ME. F. J. COLE ON THE STRUCTURE AND MORPHOLOGY OF been found necessary to study details, and to include in the investigation whole subjects not contemplated in the beginning." The more important additions are the sections on the lateralis accessorius (which I trust is here correctly understood for the fii'st time), the phytogeny of the lateral canals, the relations of the latter to the auditory organ, the metamerism of the lateral sense organs, and the morphology of the " facial " ganglion and Jacobson's anastomosis. Hence the somewhat comprehensive title of the present communication. C. Sensory Canals in General. The sensory canals of the Cod differ in no essential respect from those of the typical form. Indeed the uniformity that exists in this connection, even amongst fishes of widelv different classification, is one of the most remarkable incidents in the history of this remarkable system. The same fundamental plan may be seen in all, whether we take an Elasmobranch, a Holocephalan, a Dipnoan, a "Ganoid," or a " Teleostean." Even in the Palaeozoic Coccosteaus and Asterolepids, we see, thanks to the admirable and laborious researches of Traquair, the same generalised type. In Coccosteus, for example, we may consider the horizontal canal traversing the anterior dorso-lateral, ihe external occipital, and the central plates, as the lateral or body canal. This, after a break, gives rise to a supra-orbital canal, traversing the central and pre-orl)ital plates, and an infra- orbital, situated on the central, post-orbital, and maxillary ossicles. Tliere is also a supra-temporal commissure situated on the two centrals, and this probably marked the anterior extremity of the lateral canal. The hyomandibular series is represented by canals on the post-orbital, marginal, and maxillary, and perhaps by the other canals in this region. In PtericJithi/s, again, the sensory canals are very simplified, being reduced to representatives of the lateral and iafra-orbital canals, the former being connected anteriorly on the median-occipital plate by the supra-temj)oral commissure. Here the practical absence of a supra-orbital canal is perhaps correlated with the curious condition of the orbits in the Asterolepid fishes. As I have elsewhere maintained (46, p. 181), and as the pioneer researches of Allis must be held to have established, the sensory canal systems of fishes, both recent and fossil, may be reduced to a common type. Pending the production of weighty evidence to the contrary, this must be considered as one of the best-established conclusions attained by the careful study of these organs by many able observers. This common type may be summarised as follows : — (1) A supra-orbital canal passing, as its name implies, over the eye. Innervated by the superficial ophthalmic lateral line nerve. Anteriorly may anastomose with the infra-orbital canal or end blindly ; posteriorly anastomoses either Avith the infra-orbital or lateral canal, but more often with the former. (2) An infra-orbital canal coursing underneath the eye. Innervated by the buccal -l-otic lateral line nerves. Anteriorly may anastomose with the supra-orbital canal or end blindly ; posteriorly anastomoses either with the lateral canal only or with both the supra-orbital and lateral canals (usually). THE CRANIAL NEKVES AND LATERAL SENSE ORGANS OF FISHES. 121 (3) A hyomandibular or operculo-mandibular canal. Developed in connection witJi the lower jaw, and may be represented by one or more canals. Innervated by the external mandibular lateral line nerve. Ventrally may anastomose with its fellow or fellows of the opposite side, but usually ends blindly ; dorsally usually anastomoses with the infra- orbital canal, may in some cases do so with the lateral canal, may anastomose with botli these canals, or may remain independent of any. Figure of Gadus virens. half natural size, showing the sensory canals and their innervation — the latter imlicatefl by the different kinds of shading. D.F. anterior extremity of dorsal fin; Z,'. supra-temporal portion of lateralis canal ; L\ lateral portion of lateralis canal ; iV\ anterior and posterior narial openings ; 0. opercular fold ; PcT.F. pectoral fin; Plv.F. pelvic fin; P.O. pit orgms (innervated by the lateral line nerves) ; S.O.C. supra- orbital commissure. (1) Supra-orbital canal, S.O. Innervated by superficial ophthalmic lateral line nerve — eroBS-hatched. (2) Infra-orbital canal, F.O. Innervated by buccal + otic lateral line nerves — dotted. (S) Hyomandibular or Operculo-mandibular canal, H. Innervated by external mandibular lateral line nerve — longitudinal shading. (4) Lateralis canal, D and L'^. Innervated by lateralis lateral line nerve — oblique shading. (4) A lateral canal situated at the side of the body. Innervated by the lateralis lateral line nerve. Anteriorly anastomoses usually with the infra-orbital canal only, but may also do so with the supra-orbital canal ; posteriorly ends blindly at the tail. The canal known as the supra-temporal or occipital commissure ( = Commissural canal of Ewart) has somewhat variable relations, and is perhaps not homologous in all fishes. 122 ME. F. J. COLE ON THE STRUCTURE AND MORPHOLOGY OF Strictly speaking, and arguing from its condition in those fishes in which its innervation has heen carefully ascertained, it should form a dorsal connection hetween the anterior extremities of the lateral canals. It may, however, interpolate itself, as it does in Cliimcera and other recent fishes, and perhaps also in Pterichthys, hetween the two orhital canals, so that these do not anastomose posteriorly, hut hoth arise from the lateral canal. But, however this may he, no canal can he considered a supra-temporal canal which is not innervated by the lateralis nerve, and which therefore is not a portion of the latei-al canal. I hence propose to describe the sensory canals of Oadus morrJiim in the following order : — (1) Supra-orbital canal ; (2) Infra-orbital canal ; (3) Hyomandibular canal ; (4) Lateralis canal. All these canals will be described from before backwards. D. Sensory Canals of Gabus morrbua. (PI. 21, fig. 1.) (1) Supra-orbital Canal. The supra-orbital canal commences blindly at the anterior extremity of the nasal bone, and therefore of course at the extremity of the snout. This blind extremity appears very late in the ontogeny of the system, and is not seen in sections of young Gadids — the canal here being directly continuous Avith the first dermal tubule (I propose to designate as " dermal tubules " those small tubes by which at intervals the main sensory canals communicate with the surface *). The supra-orbital canal on the nasal bone pursues a slightly sigmoid course obliquely inwards, upwards, and backwards, and measures whilst on this bone about 40 mm. long. The nasal is deeply grooved to receive the base of the canal, and its inner edge is jmrtly turned outwards to form a rough tube — imperfect, however, dorsally and externally. Anteriorly the bony nasal furrow is imperfect ventro- lateially, in order that the fii'st dermal tubule may enter the supra-orbital canal (see PI. 21). The second dermal tubule enters the supra-orbital canal 25 mm. from the posterior extremity of the nasal, and lies in a backwardly-directed oblique furrow situated on the lateral wing of the nasal. The canal now leaves the nasal and for a distance of about 5 mm. has no bony floor, but only a ligamentous one. An internal wall and roof are, however, partly supplied by a forward projection of the frontal. The third dermal tubule enters the canal at this region, but somewliat nearer the frontal than the nasal. The remainder of the supra-orbital canal on the frontal is more conveniently described from behind forwards. In front of its anastomosis with the infra-orbital it courses inwards and forwards for a distance of about 20 mm. It then enters by a lateral foramen a canal bored in the substance of the frontal. Tiie median portion of this canal forms a perfect tube, but posteriori}^ the roof is imperfect owing to the jiresence of a * The dermal tuLules and sense organs of the lateral canals are enumerated in order from before backwards in full knowledge of Allis's important proof of the relation between the sense organs and the tulnilcs. Any scientific enumeration of these structures in the ease of the Cod is, however, impossible until the development of both has been investigated, and any attempt therefore to do so here would be purely arbitrary and misleading. THE CEANIAL NEEVES AND LATERAL SENSE ORGANS OE FISHES. 123 long, laterally compressed, oval median fontanelle, which measured 12 mm. long in the present sjDCcimen. The posterior extremity of this fontanelle represents the nearest approach which the supra-orbital canal makes to the mid-dorsal line, the two supra- orbital canals being only separated at this region by a cylindrical bony basal projection or septum 3 mm. wide. It is here that the two supra-orbital canals communicate Ijy a well-marked transverse commissure, very obvious in sections of young Gadids, but apt to be overlooked in dissections of adults. In front of this region the canal at once liegins to course obliquely outwards, and continues to do so as far as its anterior extremity. The bony septum above I'eferred to becomes wide at the anterior extremity of the fontanelle, where it is nearly 5 mm. wide. The median closed portion of the tube is a little over 10 mm. long, in front of which the next 14 mm. of the canal are imperfect externally, becoming more and more so anteriorly. The course of the supra-orbital canal from the posterior extremity of the median fontanelle up to tlie anterior edge of the frontal has been slightly obliquely outwards and forwards. The fourth mipaired dermal tubule, which is the longest of those opening into the supra-orbital canal, enters it at the short transverse commissure. The surface pore in adults is, in all the specimens that I have examined, slightly to the left of the median dorsal line, whilst the tubule itself opens precisely at the centre of the commissure, although I have seen it also somewhat to the left. In sections of young Gadids, however, both the surface j)ore and the internal opening are exactly median — another instance of the slight disturbance of the symmetry of the lateral line organs which lakes place in the adult. It may be mentioned here that this is the only unpaired dermal tubule in the Cod. (2) Iiifra-orhital Canal. This will be described under the headings of the various bones which support it. First Suh-orhital or Lachrymal Bone *. — The infra-orbital canal arises blindly a little in front of the lachrymal near the mid-dorsal line at the extremity of the snout; The blind extremity exists from the very beginning, and is obvious both in sections of young forms and in dissections of the adult. The anterior extremity of the lachrymal is grooved to receive this part of the infra-orbital canal. The lachrymal itself is roughly triangular, with the apex directed forwards. Its length is about 60 mm., and breadth at the base over 35 mm. The base may be divided into two concave portions, separated by a median * The synonymy of the bones of the Teleostean skull is, it is hardly necessary for me to point out, a somewhat obscure subject. I have endeavoiu-ed as fur as possible to steer a middle course, and therefore hope that no objection can be taken to any of my terms. It is, perhaps, necessary to exjilain that Allis (6) and other authors consider the first sub-orbital and lachrymal to he two separate bones. No reasonable objection, however, can be brought against the view advocated by McMurrich (136), that the lachrymal is a modified sub-orbital plate, and I therefore describe it as the first sub-orbital. "We may note in this connection that the Teleostean lachrj-mal has been erroneously termed by some authors the pre-frontal. The correct homologue in the Teleosts of the Ganoid pre-froutal is, however, the lateral ethmoid (=the parethmoid). For the rest, sphenotic and pterotic are undoubtedly synonyms of post-frontal and squamosal respectively (but see p. 132). The confusion in the nomenclature of the bones of the fish's skull has arisen partly by the misuse of some terms and partly by the unnecessary introduction of others. SECOND SERIES. — ZOOLOGY, VOL. VII. 18 124 ME. F. J. COLE ON THE STRUCTUEE AND MOEPHOLOGY OF prominence, the ventral portion bearing a facet for the articulation of the second sub-orbital. The sensory canal passes along the middle of the bone, marking it into two almost equal halves. The dorsal border of the canal is slightly sigmoid, and anteriorly it aj)proaches the border of the upper jaw, whilst the direction of the whole canal is distinctly downward. A thin bony lamina (see below) projects downwards from above and forms a roof and an external border for this portion of the infra-orbital canal, leaving it open, however, ventrally. About 35 mm. from the posterior extremity of the lachrymal this bony lamina is seen to be l)roken, thus forming a sort of notch and leaving this portion of the infra-orbital canal wdthout any external boundary, and with only a portion of its roof. The first four dermal tubules open into the iDfra-orbital canal on the lachrymal, the first at the anterior extremity of the bone, and the tbird at the notch mentioned above. The articulation of the lachrymal with the second sub-orbital is somewhat peculiar and may here be descrilied. As mentioned above, and as is the case with the other sub-orbitals, the lachrymal sends down externally a bony lamina the function of which is to protect the external wall of the infra-orbital canal. With the posterior extremity of tbe imperfect tube thus formed the dorsal portion of the anterior convex extremity of the second sub-orbital becomes fitted or wedged in. Ventral to the external bony lamina the second sub-orbital simply overlaps the lachrymal, and the large facet thus formed at the posterior extremity of the latter bone measures 6 mm. antero-posteriorly. Second Sub-orbital. — The direction of this ossicle is backw^ards and downwards. Its length dorsally at the sensory canal is about 20 mm., and its greatest width 22 mm. Tlie anterior articular surface is convex, and is connected with the lachrymal in the way above described. Posteriorly there is an oblique articulation with the third sub-orlntal. The second sub-orbital is a large semi-cartilaginous plate, the dorsal border of which is turned over so as to form a stout support for this portion of the infra-orbital canal. As, however, the dorsal border does not fuse on to the large body of the plate ventral to the sensory canal, the tube is imperfect ventrally, and is, in fact, only comj)leted by the ligamentous sheath of the ossicle. The dermal tubules 5 and 6 open into the infra- orbital canal on this ossicle — the former at the anterior extremity, where it overlaps tlie lachrymal, and the latter near its posterior border. Third St(l)-orbital. — This ossicle continues the downward direction of its predecessor, but is somewhat more horizontal. The infra-orbital canal is still passing backwards and downwards. The length of the third snb-orl)ital is 15 mm., and its width 16 mm. The anterior and posterior articular surfaces are oblique and roughly parallel, but the anterior is much the longer. An imperfect tube for the lodgment of the sensory canal is formed in the same way as in the second sub-orbital. The seventh dermal tubule opens into the canal at the posterior extremity of the third sub-orbital. Fourth Sub-orbital. — The infra-orbital canal now begins to take an upward turn, and, in consequence, the direction of this ossicle is upwards and backwards. It is further midw^ay betw ecu the vertical and horizontal sub-orbitals, and measures 14 mm. in length and 7 mm. in width. The sub-orbitals thus narrow from before backwards. The sensory canal tube is formed similarly to those on the preceding sub-orbitals, but it must be noted THE CRANIAL NEEVES AND LATERAL SENSE ORGANS OF FISHES. 125 that as the sub-orbitals become narrower, so the edge turned over to form the tube approximates more and more to the ventral or posterior edge, the tendency thus being for the whole of the sub-orbital ossicle to be nsed up in the formation of the protective sensory tube. The eighth dermal tubule opens at the dorsal or posterior extremity of the ossicle, the latter tapering off to receive it. Fifth Sub-orbital or First Post-orbited. — The iufra-orbital canal has by this time taken a sharp upward curve, so that the fifth sub-orbital is not far removed from the perpendicular. Its length is 17 mm., and the anterior edge almost approximates to the posterior in the formation of the tube lor the iufra-orbital canal. The ninth dermal tubule is received by the infra-orbital canal betweca the fifth and sixth sub-orbitals. This tubule is not rej)resented in Gaclus virens. Sixth Sub-orbital or Second Fost-orbital. — This, the last and most posterior sub-orbital, articulates ventrally with the fifth sub-orbital, and dorsally with the postero-lateral region of the frontal, and also slightly with the post-frontal or sphenotic. Its direction is as near as possible perpendicular, and the portion of the infra-orbital canal that it lodges is of course directly continuous with that on the frontal. The length of the canal on the sixth sub-orbital is 14 mm., and it is protected in a precisely similar manner as on the fifth sub-orbital — the anterior and posterior edges not quite approximating. Frontal. — The infra-orbital canal is now on the frontal. Situated on the upper surface of the postero-external angle of the frontal is a triangular fossa with the apex directed inwards and forwards. The base of the triangle forms a portion of the posterior edge of the frontal. The infra-orbital canal comes first along the outer side of the ti-iangle (a distance of about 14 mm.), and arriving at the apex first of all anastomoses with the supra-orbital canal, and then turns sharply backwards, edging the inner side of the triangle (about 15 mm.). The canal, therefore, at this region turns first inwards and forwards, and then outwards and backwards. The two sides of the triangular fossa on the frontal are depressed so as to form slight furrows for the reception of the base of the infra-orbital canal. Further, the inner side of the triangle is raised up and arches outwards, thus forming a roof for this portion of the infra-orljital canal. As, however, elsewhere, the tube is imperfect externally. Post-frontal or Sphenotic. — The sphenotic now comes to the surface and lodges the next 5 mm. of the infra-orbital canal, the latter stUl pursuing the downward and backward direction of the portion immediately preceding it on the frontal. The sphenotic, however, only supports the floor of the infra-orbital canal, an inner wall and roof being here formed partly by a backward projection of the frontal and partly by a forward prolongation of the pterotic. Externally the sensory canal is only protected by ligament. The tenth dermal tubule enters the canal at about the middle of the sphenotic, and in front of the canal in that bone transmitting the otic branch of the outer buccal nerve. Squamosal or Pterotic. — The iufra-orbital canal, leaving the sj)henotic and still passing backwards and somewliat downwards, enters on the pterotic, which supports it for the last 30 mm. of its length, until, between the pterotic and the succeeding supra-temporal, the infra-orbital canal anastomoses with the lateral or body canal. A more or less perfect 18* 126 ME. F. J. COLE ON THE STEUCTUEE AND MOEPHOLOGY OF tube is formed on the pterotic by a latero-external process being sent down. Posteriorly this process only forms an imperfect tiibe, but anteriorly it usually almost completely encloses the canal, yet does not fuse ventrally with the floor of the ossicle. The tube is thus imperfect for the whole of its length, but less so anteriorly than posteriorly. The last or eleventh dermal tubule of the infra-orbital canal opens into it between the pterotic and the adjoining supra-temporal, but the greater part of the aperture is on the pterotic. (3) Hi/omandihula r Gmial. The hyomandibular canal arises on the dentary at its anterior extremity near the symphysis, its length, whilst on this bone, being about 80 mm. The direction of the canal depends, naturally, on the position of the lower jaw. When the jaw is closed the canal has a stioug upward incline. Its relations with the articular portion of the canal are, of course, fixed, and do not vary with the gape of the jaw. The hyomandibular canal fits into a deep groove on the ventral surface of the dentary which is continued almost to the anterior symphysis. This groove is widely open ventrally, and gradually tapers towards its anterior extremity. The first five dermal tubules open into the hyomandibular canal whilst on the dentary, the sixth opening at the junction of the dentary and articular, but rather on to the dentary. Leaving the dentary the hyomandibular canal passes on to the articular, and then begins the upward curve which carries the canal on to the pre-operculum. Strong dorsal and ventral ridges form a stout protection for the canal, which is only exposed externally. The hyomandibular canal is 15 mm. long on the articular. Owing to an inward shelving on the part of the articular and pre-operculum, the next 10 mm. of the canal have no bony support, but are protected only by a ligamentous sheath. This, of course, is developed in connection with the movement of the lower jaw. There is also a strong upward curve on the part of the canal to meet the succeeding portion on the pre-opei'culum. The seventh dermal tubule opens on to the canal at about the middle of this ligamentous section. Having reached the pre-operculum, the hyomandibular canal lies at first somewhat horizontally. It then takes a graceful curve upwards, so that the posterior portion of the canal is practically vertical. Whilst on the pre-operculum the hyomandibular canal has a length of about 80 mm. A thin bony lamella projects downwards anteriorly and backwards posteriorly, forming an external lateral wall for the canal, but, however, leaving it open ventrally in front and posteriorly behind. Commencing at about 11 mm. from the posterior extremity of the canal, a ridge of bone 8 mm. long is seen to be thrown up, which forms a posterior wall for the canal. At this region the anterior bony lamina forming the external lateral wall of the canal tapers down, otherwise the hyomandibular canal would in this region be completely enclosed in bone. The tube then is here also incomplete externally, but is inore perfect than it is at any other part of the pre-operculum. The hyomandibular canal ends blindly 10 mm. below the dorsal extremity of the pre-operculum. The dermal tubules eight to twelve open on to the THE CRANIAL NERVES AND LATERAL SENSE ORGANS OF FISHES. 127 canal at the pre-opei'culum, the eleventh helow and the twelfth ahove the ridge of bone just mentioned. It is thus seen that the hyomandibuiai- canal is perfectly independent of any of the others, and does not anastomose either with the infra-orbital or lateral canals. (4) Lateralis Canal. First or Supra-temporal Portion. As with the infra-orl)ital canal, it will bo most convenient to describe the lateral canal under the headings of its various supjiorting ossicles. First Supra-temporal or Extra Scapula.— The supra-temporal canal commences b lin dly in both G. morj^hua and G. vij'ens at the anterior extremity of the first supra-temporal ossicle. Its direction is markedly inwards and forwards. The greatest length of the ossicle is 17 mm., and its greatest breadth 6 mm. It is free anteriorly, that is, it has no articulation with any otlier bone, but its extremity is attached by a ligament to the dorsal spiny process of the parietal overhanging the foramen transmitting the so-called " cutaneous branch of the Vth." * Posteriorly the ossicle articulates by means of an oblique convexity with tlie second supra-temporal. The first supra-temporal consists of an internal plate, having its dorsal edge turned over somewhat considerably to protect the supra-temporal canal. Anteriorly the portion turned over tapers down to admit of the entrance into the canal of the first or proximal dermal tubule. Second Supra-temporal or Extra-scapula. — Supports the distal or basal portion of the supra-temporal canal, and consists of an internal plate, the two edges of which have more or less become opposed to form a tube. Posteriorly this apposition is complete, so that the tube is here perfect, thougii the two edges in question have not fused, such not being a characteristic of the Cod. Anteriorly, however, the tube, as in most of the other lateral line ossicles, is imperfect, but this is to enable the second dermal tubule to eater the canal. The upper posterior border of the ossicle bears a semicircular notch, which fits into the upper or epiotic limb of the post-temporal. The internal face of the second supra-temporal also rests on this limb of the post-temporal. The greatest length of the second supra-temporal is 17 mm., and its greatest width about 11 mm. Anteriorly it presents a concave border for articulating with the first supra-temjooral, whilst posteriorly it articulates with two ossicles : a, by a long, slightly convex, ventral facet with the third supra-temporal ; b, by a backwaixlly directed posterior facet (slightly concave) with the fourth supi"a-temporal. Posteriorly the supra-temporal portion of the lateralis canal takes a dowuAvard curve and becomes confluent with the latei-al or body portion. Second or Lateral Portion. The first 20 mm. of this section of the lateral cjinal are supported partly by the third supra-temporal, biit also partly by the ventral jiortion of the second (see PI. 21. fig. 1). This fact must be taken into consideration when reading the description of the former ossicle. * =the R. lateralis acoessorius (sec Section N, p. 16G). 128 MB. F. J. COLE ON THE STEUCTURE AND MORPHOLOGY OF Third Supra-temporal or Extra-scapula. — The third supra-temporal is a somewhat long bone supporting tlie anterior extremity of the lateral canal as it passes downwards and backwards from the pterotic. Its greatest length is 22 mm., and its greatest width 9 mm. It consists of a plate slightly convex intei*nally, the dorsal edge of which is turned over, but not very markedly, to form an imperfect tube. Its ventral border is quite straight, whilst its dorsal border is somewhat irregular. Anteriorly it articulates by means of an obliqvie and well-marked concavity with the pterotic, the dorsal border of the third supra-temporal being prolonged forwards so as to fit into a corresponding shelving on the pterotic. Ventrally the latter presents a large triangular facet 10 mm. in length from base to apex, on w^hich the ventral portion of the anterior extremity of the third supra-temporal rests and articulates. This articulation is very compact and strong. Posteriorly the articulation is with two ossicles : a, by a long dorsal and slightly concave facet with the second supra-temporal ; b, by an oblique concavo-convex facet with the fourth supra-temporal. The third dermal tubule opened into the lateral canal near the posterior extremity of the third supra-temporal, and slightly posterior to the entry of the supra-temporal canal into the lateral. This tubule was present on the left side of the fish, but not on the right. Fourth Supra-temporal or Extra-scapula. — This consists of a flat internal plate 11 mm. across at its widest part, and with a maximum length of 16 mm. Its dorsal edge is turned over so as to form an external jirocess protecting the sensory canal. Anteriorly it has a close ligamentous articulation with two ossicles : «, by a convexo-concave ventral facet with the third supra-temporal ; h, by a slightly convex dorsal facet with the second supra-temporal. The latter facet is internal to the first and passes back at an angle to it. Posteriorly the fourth supra-temporal rests on and overlaps the angle formed by the two forks of the post-temporal. The fourth dermal tubule opens into the lateral canal near the centre of the fourth supra-temporal. Post-temporal or Supra-scapula *. — The angle formed by the union of the two limbs of the post-temporal now comes to the surface of the skull and supports the next 9 mm. of the lateral canal. It is here that the lateral canal commences to approacli the surface of the body and to take tip that position in which it is to be found immediately under the skin. The fifth dermal tubule opens just at the posterior extremity of the post- temporal, and almost between that bono and the first lateral line ossicle. Behind the post-temporal the lateral canal loses the support of the bones of the skull and pectoral girdle, and is only protected at intervals by the lateral line ossicles, which themselves diminish posteriorly as the canal approaches the skin and decreases in size. At about the middle of the fish the lateral canal lies immediately under the skin, and is situated at the side of the body, its position being indicated by the modified scales lying immediately over the canal. In the specimen from which the above description has been written, it was about 55 mm. ventral to the anterior extremity of the dorsal fin. It is supported behind the post-temporal by a series of imperfect bony cylinders, the * The suin'a-elavicle of some authors (t'. (/. McMurrich, 136, and Gegeubaur). It is imiiossible, however, to homologiso the boues usually termed post-temporal and supra-clavicle. THE CEANIAL NERVES AND LATERAL SENSE ORGANS OF FLSHES. 129 so-called "lateral line ossicles." The anterior extremity of each "lateral line ossicle" is 2:)lacecl just posterior to the internal opening of a dermal tu1:)ule, so that if we regard the lateral canal as composed of segments defined by the internal openings of the dermal tubules and the intermediate occurrence of sense organs, then the lateral line ossicles will lie at the anterior extremities of these segments. Each cylinder is imperfect externally, the space being obliterated by the periosteal membrane. The length of one taken from about the region of the pectoi-al fin was 7 mm. Anteriorly they increase in size, the first, just posterior to the post-temporal, being an irregular imperfect tube 11 mm. long. E. Gadus MoitiiHUA a:nd G. vibess compared. The differences between these two species are few but decisive. The sense and pit organs of both are the same {roughly as regards the pit-organs) both in number and position. The only variations I could find were in the dermal tubules. These will be at once noticed if a comparison be made between figs. 1 and 2, PLs. 21 & 23 (representing G. morrlma and G. virens respectively), and are as follows :— 1. The ninth dermal tubule on the infra-orbital canal of G. morrlma is absent in G. virens. This, as far as I am aAvare, is a perfectly constant difference. I have never failed to find it in G. morrlma, nor have I ever seen it in G. virens. 2. In G. virens the hyomandibular canal opens anteriorly on to the surface, but does not do so in G. morrlma. This, I believe, is another constant variation. 3. In G. morrlma the third dermal tubule of the lateral canal is of variable occurrence. In the fish from which fig. 1 was drawn it was present on the left side, but absent on the right. It will be noted that the nares also were abnormal in that fish on the left side, being fused there, but quite normal on the right side. In G. virens the fourth dermal tubule of the lateral canal of G. morrlma is, I have found, invariably absent, nor have I ever seen any fusion on the part of the anterior and posterior nares. E. The Sense Organs on the Lateral line Canals. (Plates 22 & 23.) These have been carefully worked out, as well as the number and position of the dermal tubules verified, from sei'ial sections of G. virens. This is the only method which ensures perfect accuracy in this connection. The sense-organs themselves not being obvious to the naked eye, the dissector has to rely on finding the nerve twigs supplying them. If he should chance to overlook one or more of these twigs, as often happens, the corresponding sense organs are, for the time at least, also overlooked, and this may easily nullify the results of the investigation. I accordingly paid a visit to St. Andrews and collected a large number of young " Green Cod" {G. virens), many of which have since been cut into serial sections. The heads of the living animals were cut off behind the pectoral fin and fixed in Hermann's platinum acetic osmic mixture. The sections (10 ticks thick, Cambridge rocking microtome) were stained on the slide with Mann's methyl-blue — eosin* — a most admirable method, giving perfect pictures even of the brain * Jouru. Anat. & Phys. vol. xsis. (N. S. vol. ix.), p. 100 (1894). 130 ME. F. J. COLE ON THE STEUCTUKE AND MOEPHOLOGY OF and nerve tracts. The sense organs were then systematically mapped out from the sections, so that it is hoped any possible chance of error has been removed. Suxtra-orhitul Canal. — There are five sense organs on the supra-orbital canal as against four dermal tubules. As a rule, one sense organ is placed midway between the internal openings of two dermal tubules, so that there is usually a rough correspondence between the number of sense organs and that of the tubules. The first sense organ on the supra- orbital canal is placed between the openings of the first and second dermal tubules, but nearer the second ; the second between the second and third tulmles, but nearer the third (just over the anterior extremity of the nasal sac) ; the third and fourth anterior and slightly posterior to the supra-orbital commissure respectively ; and the fifth near the posterior extremity of the canal, and in the young forms * exactly dorsal to the optic chiasma. Infra-oi'hital Canal. — This canal has eleven sense organs and ten dermal tubules. The first two sense organs are situated between the first and second tubules, and just under the first sense organ of the supra-orbital canal. There is a slight overlapping on the part of the first two sense organs, the j^osterior extremity of the first being above the anterior extremity of the second, and the two together extending practically from the opening of the first dermal tubule to the second. The next six sense organs, the third to the eighth, lie between their respective tubules as shown in the figure ; the ninth and the tenth, however, are not separated by a tubule, and this seems to imply that the ninth dermal tubule has degenerated. This tubule is indeed present in G. morrhua, and in such a position as would separate the ninth and tenth sense organs of G. vwens. It is therefore possible that in the latter species the tubule has existed and disappeared. The eleventh sense organ lies between the ninth and tenth tubules, but somewhat nearer the former. Hyomandihular Canal. — Twelve sense organs and thii'teen dermal tubviles were found in connection with this canal. The first sense organ is slightly anterior to the opening of the second tubule, and the second has the same relations with the succeeding tubule. The remaining ten sense organs are situated between the openings of the tubules as indicated in Plate 22 the last being placed on the narrow portion of the canal at its posterior extremity. Lateral Canal, — The supra- temporal segment of the lateral canal has two sense organs and two dermal tubules, the first sense organ being placed slightly posterior to the opening of the first tubule, and the second lying between the ojjening of the second tubule and the junction of the supra-temporal portion of the canal with the lateral portion. The third sense-organ is found just anterior to the junction of the two canals mentioned above, whilst the fourth is placed betweeu the third and fourth dermal tubules. The remainder of the sense organs of the lateral canal are situated as usual between the openings of the dermal tubules. The condition of the lateral canal in young Cod behind the operculum will be described and discussed elsewhere. * See note on p. 150. THE CEANIAL NERVES AND LATEliAL SENSE ORGANS OF FISHES. 131 G. Other Sense Organs belonging to the Lateral line System. (Plate 21.) Belonging undoubtedly to the lateral line system, since they are innervated by the same nerves, are the pit oi'gans or sensoi'y follicles, described by Merkel, Fritsch, AUis, and Ewart & Mitchell *. These in the Cod are somewhat laiimerous, and do not occur in the well-defined series that they do in the Elasmobranchs and Ganoids. Their structure has already been fully discussed by the authors above mentioned, so that only a few words are necessary as to their distribution. As will be seen by reference to tlie figure of G. morrhua, the pit organs cannot be separated into groups, being too irregularly scattered. It is equally obvious, however, that most of them occur in connection with the sensory canals, and this is most marked in the case of the hyomandibular canal. In spite of their apparent irregularity and number, they are very constant both in number and position, as will be ascertained by a careful examination of an adult G. morrlina and a comparison with the figure. The pit organs are usually conspicuous on account of their pigmented lips, and even where this is slight or absent a contrast in colour usually betrays their existence. As is well known, the pit oi'gans are excavated papillae formed by an invagination of the skin, and lodging a sense-organ innervated by a twig from one of the lateral line nerves. My figure (PL 21) of these organs is the result of a minute examination of the heads of several large specimens of G. morrhua. Contrasting with the numerous pit organs is tin; complete absence of any traces of Lorenzini's amiiulUe and the associated ampuUary canals. Tliis fact is duly commented on elsewhere. H. PiElation of the Sensory Canals to the Skull. That the lateral line system has no definite relations with the primitive skull is quite evident even on a priori grounds. An epiblastic structvu'e, necessarily connected with the skin, and actually found on the surface in Chim metameric significance. On p. 523, referring to Van Wij he's views above, he remarks : — "The arrangement of the sense organs and nerves of the lateral system, the regular occurrence of primary tubes between consecutive dermal bones of the head, as well as between consecutive scales of the lateral line, and the singular correspondence between the infra-orbital and opercular canals is further evidence in this same direction " [*. e. of metamerism]. I am not inclined, however, to attach much weight to these considerations. In the first place, there are too many exceptions to the regular occur- rence of the primary pores between consecutive dermal bones for this consideration to have much value *, and in the second place, although in the case of the Cod there is a * Allis says (p. 537) : — " Although some of the prima'')' tubes issue through the bone, one always issues between every two cousecutive bones along each liuo." 21* 150 MK. F. J. COLE ON THE STRUCTURE AND MORPHOLOGY OF certain correspondence between the infra -orbital and byomandibular lateral canals, it does not occur, as far as I am aware, in any other iish. And surely, in any case, the corresjiondeuce has absolutely no significance. The byomandibular canal is situated on a region morphologicaUi/ posterioi' to the infra-orbital canal, and cannot belong to the same segments or segment of the head. If the correspondence had been l)etween the supra- and infra-orbital canals (and these do not correspond either in Ainia, Gadus, or any other fish that I know of), it might have had some significance, although, I am inclined to think, very little. An interesting addition to the developmental litei-ature was made in 1891 by Wilson {225), who was the first, I believe, to discover tliat the lateral line organs and auditory organ may arise from a common sensory anlage. This seems to be oj)posed to the metameric view, bnt Wilson himself believes it to be a physiological adaptation and to have no phylogenetic significance. He favours Beard's views with regard to the head, but does not think the lateral organs of the body were primitively segmental. Cunningham (1890, 55) draws attention to the fact (p. 75) that in the Sole, " corresponding to eacli scale of the lateral line, there is a pore in the skin which leads into the dermal tube of the lateral line." On p. 81, however, he says : — " There is not a sense organ to every scale of the lateral line ; in the middle of the body there is a sense organ on every third scale : that is to say, there are two scales bearing no sense organs between two scales which bear them. The position of the sense organ in relation to the scale on which it is situated is always the same." Fig. 6, pi. xiv., shows this somewhat anomalous condition. Without impugning the accuracy of Cunningham's statement, I may point out that it is a remarkable exception to the almost universal law that there should always be at least one sense organ between the openings of two dermal tubules *. Mitrophanow (1890, 141) confirms Wilson's statement re the common anlage of the lateral line and auditory systems, and in 1892 (142) disagrees with Wilson and states his belief that the lateral organs are not metameric. In a full paper published in 1893 (143) Mitrophanow repeats his former statements, Imt adds that tlie common anlage gives rise to the auditory organ, the lateral line organs, and Beard's branchial sense organs. He considers this suflB.cient ground for maintaining that the lateral organs were not primi- tively metameric, and says this conclusion is based on the study of all the Ichthyopsid types he has investigated. Houssay (1891, 103), in an interesting review of Mitrophanow's second work above, is inclined to accept Eisig's invertebrate origin of the lateral organs, and combats Mitrophanow's statement that they are not metameric. Ayers (1892, 7) endeavours to show that the auditory organ is not supplied by a discrete cranial nerve but by the branches of two cranial nerves, /. c. the facial and the glossopharyngeal ( = tbe vagus: be considers the lateralis lateral line nerve to be a branch of the IXth). He thus favours tlie metameric view of the lateral organs. On p. 314 he says : — " As Froriep has shown, the ectodermal thickenings which Beard described as giving rise to the lateral Hne organs have in fact another fate. The genuine lateral line organs escaped Beai'd's observation, and in consequence Beard's conclusions * Sense organs may exir.t withoul dermal tubules (cp. Ewart & Mitchell, p. 10(»), but. mt viva verm. THE CRANIAL NERVES AND LATERAL .SENSE ORGANS OF FISHES. 151 as to the laomology of the vertebrate avicUtory organ are incorrect "*. Although Avers' views as to the innervation of the auditory organ cannot any longer be maintained, it is possible that his latter statement is to some extent sufficiently near the truth to require a reopening of the whole question of the " branchial " or " epiln-anchial " sense organs. In his L(cmargi(s j^aper (1892, 68), Evrart supports the view of the innervation of the lateral sense organs taken by Triant and AUis. He does not consider that Beai-d's scheme applies to the adult Elasmobranch, nor does he consider the lateral canal as composed of ontogenetic metanieric sense organs (p. 79). In his paper with Mitchell we find (69, p. 100) : — " But v/hile the sense organs and tubules have a nietamerlo arrcmgement in the trunk, there is no relation between the sense organs and segments In the head region; and, as already pointed out, some portions of the cranial canals, though possessing numerous sense organs, have no tiilnxles connecting them with the exterior. In all the cranial canals, l^cjth dorsal and ventral, there are far more sense or"-ans than segments ; e. g. in the supra-orbital canal there are nearly ninety sense organs, and in the infra-orbital there are over ninety." Pollard (1.892, 161), referring to the relation between the lateral canals and the dermal bones, in which connection we should remember Allis's statements above, says (p. 527) : — " In Clarias it is by no means a rule that pores should open at sutures " ; but on p. 539 we find the absolutely contradictory statement that " as the dermal bones are much reduced in Auchcnaspis the close relationship of pores to sutures, which exists in Clarias, is not seen." Willey (189 i<, 223) makes a somewhat remarkable statement. He says (pp. 41-i5) : " It seems certain that at first the sense organs of the lateral line must have been iuncrv^ated by spinal nerves. This follows both from ti priori considerations and also from the condition in Amphioxus, where the ectoderm of the metapleural folds is innervated by the Rami ciitanel ventrales of the dorsal spinal nerves. Under these circumstances it is necessary to supjiose with Eisig that the lateral line nerve {Ramus lateralis vagi) arose as a collector." I am unacquainted with any evidence in support of this statement. Eisig's views on the subject I have already dealt Avith, but I may mention that his explanation of the lateralis nerve has never been accepted by vertebrate morphologists. Bashford Dean (1895, 58) evidently considers the metamerism of the lateral canal a secondary modification. He says (p. 51), after considering the probable phylogeny of the system : — " The sensory cells are no longer scattered evenly along the floor of the canal ; they now occur in metameral masses supplied with a distinct nerve branch, located in the region immediately below the external tubules." Again on p. 52 he remarks : — " The original significance of the lateral line system as yet remains undetermined. As far as can be judged from its development, it appears intimately, if not genetically, related to the sense organs of the head and gill region of the ancestral fish : in resj^onse to special aquatic needs, it may thence have extended fu.rther and further backward along the median line of the trunk, and in its later differentiation acquired its metameral characters." Locy (1895, 130) agrees ndth other observers that the branchial sense organs of Beard and Froriep are not the lateral sense organs, but may perhaps corre.spond * When Ayers wrote this he must have forgotten what lie had previously written on n. 213 I 152 ME. r. J. COLE ON THE STBITCTURE AND MOEPHOLOGT OF to the segmental sensory papillre of Annelids. On p. 577 et scq. he confirms for Squalns the observations of Wilson on Set^raims and Mitrophanow on Acanthias and otlier Elasmobranclis as to the common anlage of the lateral sense organs and auditory oro-an, and states : — " MitroiAanow departs from the nsual point of view that the organs of the lateral line are metaraeric, and in that particular, I think, I should be inclined to follow him." Strong (1895, 204) is more emphatic on the point. He says (p. 197) : " It is also evident that the lateral line system has no specially segmental character, and that it cannot properly be used in the manner in which it has been attempted to use it, as a general guide in determining the segmentation of the head." Miss Julia Piatt (1896, 158) argues from the opposite point of view*. She states (pp. 502-503) : — " Since Mitrophanow claims as the result of his study that the segmenla- tion of the lateral-line system is entirely secondary, I shall be interested to discovei; when I again have my Acanthias material with me whether traces of primitive segmentation so evident in Necturus cannot also there be found, for it is dilficult to believe that the great similarity which exists in the position and direction of the main lines of sense organs in Necturus and Acai/thlas should not be the result of a similar coiirse of development." Miss Piatt also describes four of the sense organs of the infra-orbital line as being partly innervated by the ophthalmicus profundus, and concludes (pj). 530- 531) : — " I do not, for this reason, include the trigeminus among the lateral line nerves, bvit should nevertheless hesitate to say that the ' trigeminus proper does not participate in the innervation of the lateral line system.' " With regard to the ultimate fate of Beard's branchial sense organs, Minot (1897, 140) says (pp.706 & 709) : — "We have further to emphasize those traces which have been discovered of long series of sense organs, of Avhich the nose, eye, and ear are probably derivatives, in the ancestors of the vertebrates, although in all known vertebrates most of these series have become rudimentary or lost. The serial sense organs I designate under the comprehensive name of ganglionic sense organs. There are probably two, and only two, series along each side of tlie body : one series, the ujiper, corresponds to the lateral line of comparative anatomy, the other to the epibranchial line." After pointing out the diiferences between the two series, he concludes : — " The sense organ above the gill cleft [i. e. branchial or epibranchial sense organ], though differentiated, is a larval structure only, and disappears in the adult." Finally Wilson and Mattocks (1897, 226) confirm for Salmo the discovery already made by the former author in Serranus of a common anlage of the lateral and auditory sense organs, and state further that the portion in front of the auditory saucer gives rise by bifurcation to the supra- and infra-orbital canals, whilst the portion posterior to the saucer grows backwards and forms the lateral canal. We thus see that the metamerism of the lateral line nerves and their associated sense organs has for a long time been a problem, the solution of which has been attended with considei-able difficulties. The older anatomists considered the nerves to be branches of the trigeminus, facialis, and vagus, until it was shown by Priant in 1879 that the * But cp. ])p. 4!l2 and 50], which go to show thai Beaid"s branchial sense organs do not belong to the lateral line system. THE CEANIAL ]\'ERVES AND LATERAL SENSE ORGANS OF FISHES. 153 nerves usually considered to be branches of the trigemiuus really belonged to the facial. To Friaut, therefore, belongs the credit of being tlie first autlior to arrive (approximately) at the truth with regard to the innervation of the lateral sense orgaas. His work was confirmed by Marshall and Spencer in 1881 and by Mlis in 1889, and it was thus established that the superficial oplithalmic and buccal lateral Hue nerves belonged to the facial, rather than to the trigeminal, nerve. The work of Beard and Froriep in 1885, imjiortant as it is, has added considerably to the confusion wiiich exists on the subject. There can be no doubt that if the branchial or epibranchial sense organs ultimately develop into the lateral sense organs of the adult, then the latter must have been (primitively) segmental structui'es. But we have seen there is good evidence against the iilentity of the two series of sense organs, and even before this evidence transpired it is significant that the innervation of the adult lateral sense- organs could not be harmonised with the supposed embryonic conditions (cp. especially Allis and Ewart). And added to this the fact that the lateral organs and the auditory organ have been found to develop from a common sensory anlage, which discovery has been extended to several forms and has been found to apply to Elasmobraiiclis as well as to specialised Teleosts, we have an opposing view of the development of the lateral organs which has the advantage of being easily reconcilable with the facts of adult structure. This leads us to the latter view of the question. In his 1889 paper, Allis, independently following Friant, and working on the lines laid down by Marshall and Spencer, described the lateral line nerves as branches of the facial, glossopharyngeal, and vagus nerves. In this he was largely followed by Ewart (1892) and Pinkus (1894)), until it was considered completely established that the lateral nerves were undoubtedly branches of the facial and vagus, and perhaps also of the glosso- pliaryngeus. In the meantime Mayser (1882), Pollard (1892), and Strong (1895) had been working out a totally different hypothesis, the tendency of which was in the first place to regard all the lateral line nerves as morphologically branches of one trunk, and in the second to associate that trunk with the auditory irerve and system. This view was developed by me in my Cliimcera paper, in which I endeavoured to show that the lateral line system was an independent system of sense organs innervated by a distinctive and independent series of nerves of characteristic size of fibre, and further that the whole was the morphological equivalent of the auditory organ, with which it should therefore be associated. I further stated the belief that the branch of the glosso- pharyngeus innervating sense organs of the lateral line would be found on investigation to be a branch of one of the lateral line nerves, and finally, pending further investigation, provisionally associated the lateral line nerves with the facialis. These views have been entirely confirmed by recent investigations, such as tliose in 1897 by Kingsbury, Herrick, and Allis, so that the j)i"esent position, from the point of view of the comparative anatomist, and setting aside for the moment purely developmental evidence, may bo summarised as follows : — (1) The lateral line system is an indejoendent series of sense organs, differing histo- logically from any other cutaneous sensory system, such as the terminal buds described by Merkel and other authors, and not innervated by the same nerves. 154 MK. 1', J. COLE ON THE STEUCTURE AND MOEPHOLOGT OF (2) That this system is innervated by a series of lateral Hne nerves which are un- doubtedly independent of miy of the recognised cranial nerves, and are in fact mori^ho- logically branches of one trunk. (3) That the lateral line brancli of the glossopharyngeal belongs to the lateralis lateral line nerve. (4) That the lateral sense-organs and nerves are precisely comparable to the auditory organ, with which they should be associated — the lateral and auditory nerves arising from a common centre in the brain which is further peculiar to this system of nerves. It is also possible that the lateral sense organs, together with the auditory organ, in most forms arise from a common sensory anlage from the skin. We have seen that the developmental evidence in favour of the metamerism of the ]ateral line system is too conflicting to be made the basis of any discussion, but there is no room for doubt that the sense organs of the body canal are often metameric in the adult, as has been described above. It is hence necessary to enquire into the nature of this regular occiu-rence of the body sense organs. I have previously pointed out that the lateral sense organs primitively belong to the head, and have only secondarily extended on to the trunk. This can be proved both by the development and adult structure of the lateralis canal. Even in young adults of Gadiis the body canal posterior to the shoulder girdle is still very imperfectly formed, and in fact is somewhat difficult to detect in sections. In all known cases of development the body canal grows from before backwards, and its most posterior part is the last to be formed of any of tlie sensory canals. When the sensory canals are quite perfect in the head and have fully reached their adult condition, the posterior section of the body canal is still nothing more than a mere rudiment or anlage. It is hence impossible to regard any condition of the body canal as representing a primitive condition, since it is itself only a secondary structure. The innervation of this canal, however, settles the point. The nerve whicli supplies it is in all fishes the lateralis lateral line nerve, which, as it is not a collector, and is absolutely independent of the metameric nerves, must be held to disprove the essential metamerism of the body canal, and indeed shows that such a condition of this canal is purely superficial. Now it is obvious that the independent character of the lateral line system, which is such a characteristic feature of the post-embryonic conaition of existing fishes and amphibians, may be either primitive or acquired. It may be, either that the lateral nerves were originally branches of the various cranial nerves, and that the present apparent relations with the latter are the vestiges of that connection, or that the lateral nerves were primitively independent and have already commenced to fuse with, and to form an essential part of, the true cranial nerves. It seems to me that the latter conclusion, although it was advocated by myself, is being hastily and injudiciously adopted, and that further embryological investigations Avill have to be concluded before we liave sufficient data to arrive at an accurate appreciation' of the subject. The question may be viewed from the thi'ee standpoints of Embryology, Comparative Anatomy, and PalEContology. With regard to the former, in spite of the numerous and bulky memoirs that have been written on the subject by such naturalists as Dohrn, Goette, Balfoui', THE CRANIAL NEEVES AND LATERAL SENSE ORGANS OF FISHES. 155 Van Wijhe, and Beard, much has yet to be done. From an embvyological standpoint, the first alternative above is still a possible, if not a probable, explanation of the facts, and imless the evidence from Embryology is to be rejected altogether, which is out of the question, it is necessary to wait until further investigation from this standpoint definitely vipholds one view or the other. Whatever result is finally arrived at, it should be one in which both embryologists and anatomists concur, and it seems to me that this result will most probably be one that is adverse to the metamerism of the lateral organs. Comparative anatomy helps us but little. It is true that in CUmcBra, which shows us the innervation of the lateral sense organs in its simplest known condition, all the lateral nerves, except the external mandibular, arise separately from the brain, and are not in any way connected with the true cranial nerves. It is also true that as we go higher in the vertebrate scale we get every possible gradation between this comparatively independent condition and the very complex one found in the highly specialised recent Teleosteans — where the mingling between the lateral and cranial nerves is at its maximum. It is now a question of whether it is permissible to argue from this that the primitive condition must have been that in which the nerves were concentrated and independent, and therefore not metameric, since the cartilaginous fishes are simpler than the Teleostean forms, and fossil Ichthyology teUs us that they have departed less from the primitive type. Such a contention of course accepts as granted that the soft parts have advanced pari passu with the specialisation of the skeleton. It is evidence of perhaps little or doubtful value, but it may, I think, be used to confirm a view already resting on a more solid basis of fact. From Palaeontology we learn still less, and it is most valuable when it is able to throw light on the ancestry of a type that we have other reasons to believe is primitive. It shows us also that the lateral line system is an extremely archaic structure, and further that as regards the geograpliy of the sensory canals it has remained in a largely unmodified condition for untold ages. What bearing this has on the innervation of the system it would be hazardous to conjecture. Briefly, the question at issue between embryologists and anatomists is whether the lateral line system is metameric or not. The most valuable evidence that has been advanced from the latter point of view is that in which the lateral nerves have been microscopically traced both to their central origin and peripheral distribution. Considering this evidence, and pending agreement among embryologists, I take up the provisional position (which, however, I believe to be a very strong one) that it is not. I shall therefore in the present communication describe the lateral nerves as purely independent structures having no connection, other than purely secondary, with the true cranial nerves. The following description of the innervation of the lateral canals of Gadus is based partly on dissections and partly on an examination of serial transverse sections of young adult Gadus virens (="(?. carbouarms"). SECOND SERIES. — ZOOLOGY, VOL. VII. 22 156 ME. F. J. COLE ON THE STRUCTURE AND MORl'HOLOaY OF M. Innervation of the Sensory Canals in Gadus. (Plate 22.) (1) Supni-orhital Canal. Superficial Ophthalmic Trunk. — This consists of two portions, which are {a) the supei-ticial ophthalmic of the trigeminus, and {b) the superficial ophthalmic lateral line nerve. The latter arises from the posterior dorsal edge of the proximal portion of the lateral line ganglion, and at its origin lies between the ventral edge of the cerebellum and the anterior extremity of the auditory capsule. Owing to a certain amount of over- lapping on the part of the facial and auditory nerves, the origin of the lateral oplithalraic nerve is somewhat difficult to determine, owing to the close apposition of its root to the anterior edge of the auditory ganglion. It would in fact be difficult to say whether some auditoi'y fibres did not mingle with the lateral ophthalmic. There are a few ganglion cells at its base, but otherwise no cells whatever in the course of the nerve, and the few above belong, strictly speaking, to the lateral ganglion. The lateral ophthalmic now passes horizontally forwards over the trigemino-facial ganglion and soon commences to pass upwards. As, however, it leaves the ganglion, it receives a conspicuous root containing a few ganglion cells from the anterior dorsal edge of the ganglion, and this is the root of the trigeminal ophthalmic, since it is from the direct continuation of this portion of the trunk that the general sensory fibres arise. The root of the trigeminal ophthalmic is at first very flat, and closely opposed to the ventral surface of the lateral ophthalmic root, but no mingling of the fibres coidd be detected either at this region or any other. As the trunk passes gradually upwards towards the posterior poi'tion of the infra- orbital canal, the trigeminal portion becomes narrower and is almost completely separated from the lateral portion by a small blood sinus or vessel. Fui'ther forwards, however, the two nerves become approximated by passing under this vessel. By this time the nerve has entered what appears to be a rudimentary eye muscle canal, and lies opposite the ventral edge of the alisphenoid over the posterior portion of the eye, and (iu the young forms but not in the adult *) somewhat close to the brain opposite the dorsal border of the optic thalami and the origin of the optic nerves. The twig to the fifth sense organ of the supra-orbital line is given off from the dorsal or lateral portion of the trunk at this region. It perforates the wall of the eye muscle canal, passes upwards and forwards to the outside of the alisphenoid, finally piercing the frontal to reach its distribution. Continuing its course, the ophthalmic trunk passes obUquely upwards and assumes a position between the dorsal border of the eye and the supra-orbital canal. Soon after supplying the twig to sense organ 5, the lateral ophthalmic gives off a somewhat large branch [S.O.^) which, after coursing parallel with the main trunk for a short distance, * The rc4atioiis are by uo meaus the same. Fur example, a trausverse section may pass through both the optic lobes and a portion of the eye iu the young forms, whereas in the adult no such section could pass through a»y part of the lirain and eye at the same time. THE CRANIAL NEKVES AND LATERAL SENSE ORGANS OE FISHES. 157 divides into three twigs whilst still lying near the brain in the eye muscle canal and opjjosite the edge of the inner ventral process of the frontal. The inner of the three twigs passes inwards and upwards, perforates the frontal, and lies between the Irontal and the sensory canal. In this position it passes forwards for some little distance and innervates sense organ 4 of the supra-orbital line. The remaining two twigs doubtless innei'vate pit organs in this region. Opposite the point where the twig to sense organ 4 perforates the frontal, the ophthalmic trunk divides into two conspicuous nerves, a larger dorsal lateral portion, and a small ventral trigeminal portion — as is shown by the nerves arising from them, the lateral-line twigs arising from the dorsal nerve and the general cutaneous fibres from the ventral iierve. As the trunk passes forwards the division becomes more mai'ked, until two rounded nerves are distinctly differentiated. The lateral portion soon gives off a twig which passes uj)wards and enters the frontal slightly anterior to the supra-oi'bital commissure. It passes obliquely through the substance of the bone inwards and forwards, perforates it dorsally, lying between it and the sujira-orbital canal, and finally innervates sense organ 3 of the supra-orbital line. Anterior to the region where this twig enters the frontal, the two divisions of the ophthalmic trunk begin to approximate and once more continue their course together. At this region too, a small blind sac is seen in the sections to open into the supra-orbital canal external and opposite to tlie supra-orbital commissui-e and partly opposite the fourth sense-organ. It contains no sense organs and no lateral line twigs could be traced to it, and seems to me to correspond precisely to a much larger but otlierwise similar structure in the same position described by Hyrtl in Lota. It therefore possibly represents a degenerate or modified dermal tubule. In the region of sense organ 3 the supra-orbital trunk shows a tendency to split up again, and can clearly be resolved into its two constituents with the higher power of the microscope. This tendency, however, is soon lost and the nerves become inseparable as before. It is here, moreover, tliat the ojilithalmic trunk leaves what I take to be the eye muscle canal, and becomes for the first time perfectly round in transverse section. It immediately enters the frontal at the junction of the frontal and pre- frontal (= lateral ethmoid or parethmoid), and courses obliquely inwards and forwards in the spongy sub- stance of tlie frontal. After leaving the latter bone it enters a large space bounded above and internally by the frontal and below by the pre-frontal. Anterior to this sjmce the trunk begins to pass ujiwards and inwards towards the Ligamentous portion of the supra- orbital canal, which it accompanies, and an examination of it with the high power at once reveals the distinctiveness of its lateral and trigeminal portions. These again separate, and the ventral portion or trigeminal ophthalmic gives off a large nerve, which could not be satisfactorily traced in the sections, bvit seemed to be a cutaneous sensory nerve *. In front the two ophthalmics again more or less approximate. Before leaving the space in the frontal mentioned above, the lateral ophthalmic gives off dorsally a twig {S.O.^) which passes inwards and forwards, curves upwards round the * The fibres of this nerve undoubted!}' came from the trigeminal ophthalmic. 22* 158 MK. F. J. COLE ON THE STRUCTURE AND MORPHOLOGY OF anterior edge of the frontal, between the latter and the ligamentous portion of the supra- orbital canal near the mid-dorsal line, to the inner side of the sensory canal, and was traced almost on to the skin and then lost. It most probably supplied the pit organs in that region. Coincident with the ligamentous portion of the supra-orbital canal, the ophthalmic trunk separates into its two components, quite obvious with the low power, the lateral constituent being dorsal and the larger of the two. The latter soon afterwards gives off a twig which perforates the posterior edge of the nasal, lies between the latter bone and the supra-orbital canal, and Anally passes obliquely inwards and forwards to supply sense organ 2. • The ophthalmic trunk has now completely split up, both components at first lying close together at the posterior extremity of the nasal, ventral to the latter bone and just below the supra-orbital canal. Opposite the second sense organ the two components commence to run alongside again, but do not mingle. Anteriorly the lateral, together with the greater portion of the trigeminal, ophthalmic pass inwards and upwards along the inner face of the nasal, and whilst there a trigeminal twig is given off (S.O.^) which, passing outwards and upwards along the outside face of the nasal, is distributed to the skin in that region. Whilst the ophthalmic nerves are passing along the inner face of the nasal the relation between them is for the first time changed, the smaller trigeminal curling round the larger lateral ophthalmic and assuming the dorsal position. Opposite the anterior extremity of sense organ 2 the two components finally separate out and do not for the remainder of their course come into contact again *. The smaller dorsal trigeminal ophthalmic (S.O.^) passes rapidly upwards, dividing into two, is distributed to the skin of the dorsal region of the snout, and, although coursing with the lateral line nerve described in the footnote, is not in any way connected with it. The large ventral lateral ophthalmic, on the other hand, jiasses forwards, perforates the nasal opposite the opening of the second dermal tubide, and terminates in sense organ 1. (2) Infra-orbital Canal. Buccal Trunk. The buccal trunk, leaving the ophthalmic and buccal ganglion, passes downwards and outAvards through the " trigeminal " portion of the trigcmino-facial complex, and whilst passing through this ganglion divides into the nerves (1 and 2 below) which issue from the ganglion at different levels. (1) Outer buccal branch. — Issues from the trigeminal portion of the V-VIIth ganglion dorsal and posterior to the second branch. It is smaller than the latter, and gives off', * Just at. this region a long nerve from the upper ramus of the inner buccal lateral line nerve passed straight up, crossed the tvro ophthalmic nerves internally, but was not connected with either, curved outwards and round the dorsal edge of the nasal, and finallv passed downwards to innervate a pit organ opposite the anterior extremity ot sense organ 1. This curious nerve is not represented in other fishes, and probably consists of lateral superficial ophthalmic fibres following a buccal course. THE CRANIAL ISTERVES AND LATERAL SENSE ORGANS OF FLSHES. 159 immediately after leaving the ganglion, tlie otic nei've, being thereafter continued on to the orbit as the posterior or outer buccal nerve of the buccal trunk. Both these nerves are described below. Coursing for a time alongside the outer buccal branch and issuing from the "trigeminal" ganglion immediately ventral to it, in fact from the maxillo-mandibular portion of the ganglionic complex, is one of the nerves described by Strong as " accessory branches of the trigeminus," and also mentioned by Allis (6, p. 605, &c.). The nerve now described undoubtedly corresponds to AUis's nerve " c " from the maxillo-man- dibular trunk, and is distributed mostly to the tissues behind and below the eye. Also issuing from the ganglion at the same level, but posterior to it, and passing at first outwards and then downwards, is a twig which seems to tally with AUis's branch of the inferior maxillary " r.lap.do.''' (6, p. 610), since I traced some of its fibres to the dilator- operculi muscle. (2) Inyier buccal branch. — Leaves the ganglionic complex ventral and anterior to the first nerve. As it issues from the ganglion and passes into the orbit it is joined and accompanied by the maxillo-mandibular trunk, but lies dorsal and somewhat posterior to it. There is, however, never any connection between them, and sections show the inner buccal branch to be perfectly distinct, from its origin at the ojihthalmic and buccal ganglion onwards. The maxillo-mandibular trunk soon begins to separate into maxillary and mandibular nerves respectively, and as it does so the inner buccal branch passes upwards so as to lie dorsal to the superior maxillary, when the separation of the maxillo- mandibular trunk is complete. (I may here remark that the relative positions of the inner buccal and trigeminal nerves in the orbit are subject to some variation. The con- dition just described is shown in my second figure. In the sections, however, and in. other dissections the inner buccal and its two rami were situated below the supeiior maxillai'V throughout the whole orl^it.) In front the inner buccal crosses over the superior maxillary so as to lie ventral to it. As it crosses the orbit, and just over the division of the maxillo-mandibular trunk into its two derivatives, the inner buccal branch divides into a smaller inner and dorsal portion, and a larger outer and veutral one. These will be described respectively as the upper and lower rami of the inner buccal branch of the buccal trunk. Outer buccal branch. Otic nerve. — This nerve arises from the outer buccal branch immediately the latter emerges through the pro-otic notch, and then passes straight upwards but slightly backwards, accompanied by an arterial twig, over the pro-otic and the external face of the post-frontal, until it reaches a backwardly-directed dorso-ventral canal bored in the substance of the post-frontal. Having passed through this, it emerges on the dorsal surface of the skull between the post-frontal and the anterior overlapping portion of the squamosal. It then passes straight backwards over the squamosal, lying dorsal to the latter bone and ventral to the infra-orbital canal, until it reaches the last or 11th sense organ of the infra-orbital line which it suj)plies. Outer buccal branch. Outer buccal nerve. — On leaving the ganglion, this nerve passes forwards and downwards. It soon gives off a twig which, travelling upwards and for- wards, pierces the sixth suborbital and supplies sense organ 10 of the infra-orbital canal. 160 MR. ¥. J. COLE ON THE STKUCTURE AND MOKPJIOLOGY OF Beyond this the outer bviccal takes a sharp turn downwards, but before doing so crosses internally the vert