ete Wit, Ae if bru pa a ied ANA we 47 ere VF Pee vent it is i es peed i ( dee) paws , ‘ ay ‘ H F , Neate on sat i Seager : Heyer en gy NA A alana ee : Seat asin, Pa ert bai ih bir ee Wd ‘ EN At ; Fura PEG Rn i ! ary Ch te ys! i WH W foi of i na it aS the i ay et re ht aa 4 Netra EE Fe Pe eet gl ve HE | 4 ea cay aut at Pt ny einai uit Sabri i ae hoya “ K Geygy MA eH RGF RR a sees (aie Sera wate carey PROCEEDINGS OF THE GENERAL MEETINGS FOR SCIENTIFIC BUSINESS OF THE ZOOLOGICAL SOCIETY On WOnN D OUN: 1921, pp. 1-446, witH 17 PLATES AND 157 TEX'r-FIGURES. i ear 23)) PRINTED FOR THE SOCIETY, SOLD AT ITS HOUSE IN REGENT’S PARK. LONDON: MESSRS. LONGMANS, GREEN, AND CO. PATERNOSTER ROW. IG Wis it OF THE COUNCIL AND OFFICERS OF THE ZOOLOGICAL SOCIETY OF LONDON, oz Patron. His Magesty Tus Kine. COUNCIL. His Grace Tue Duxe or Beprorp, K.G., F.R.S., President. ALFRED H. Cocks, Ese., M.A. CuarLes Drummonp, Esq, Treasurer. ALFRED Hzra, Esq., O.B.E. THe Rieuy Hon. 'THE Viscount Gru keGw ese: Siz Sipney F, Harmer, K.B.E., IAN, TSGIDL5 WLRS, aa President. Pror. James P. Hitt, D.Sc., E.R.S., Vice-President. WitiramM Huntsman, Esq. Masor Tur Lorp Atasrair Roserr [nnes-KeEr. Pror. Ernest W. MacBripe, D.Sce., F.R.S., Vice-President. Cot. Sir Henry McMaunon, GEO AMIE Gir liable E. G. B. Mrapre-Watpo, Esq., Vice-President. P. Coatmers MrrcHet, Esq., Opler ithe IME IDES; JU.) DL, F.R.S., Secretary. THe Karu or Onstow, O.B.E. Masor Apert Pam, O.B.E. THe LorD QuEENBOROUGH. His Grack THE DvKke or Ruttanp, K.G. Mavsor Ricuarp S. Taytor. A. TREvor-Barryz, Hsq., M.A. Antuony H. WINGFIELD, Esq., Vice-President. A. Smira Woopwarp, Esq., LL.D., F.R.S., Vice-Pre- sident. PRINCIPAL OFFICERS. P. Cuatmers Mrrcnety, C.B.M., M.A., D.Sc., LL.D., F.R.S., Secretary. R. I. Pocock, F.RS., F.LS8., Curator of Mammals and Resident Superintendent of the Gardens. D, Sere-Surru, Curator of Birds and Inspector of Works. Epwarp G. BouLENGER, Curator of Reptiles. Miss L. KH. Curesman, F.E.S., Curator of Insects. h Prof. R. 'T. Lerpur, D.Se., M.D., Director of Prosectorium. Dr. C. F. Sonnac, Ch.B., Anatomist. Dr. N.S. Lucas, M.B., Ch.B., Pathologist. Dr. G. M. Vuvers, M.R.C.S., L.R.C.P., Hon. Parasitologist. F. Martin Duncan, F.R.M.S., Librarian. H.W. Bonn, Accountant. W. H. Coun, Chief Clerk. \) LIST OF CONTENTS. 1921, pp. 1-446. EXHIBITIONS AND NOTICKS. The Secretary. Report on the Additions to the Society’s Menagerie during the months of November and Wecennoe rele Oi ere lve teal Sao ne ao A a eae Mr. E. G. Boutencer, F.Z.S. Exhibition of, and remarks upon, a Black Salamander (Salamandra atra) ......... reo. dis 125 Jebwai, TIS 14s," isdenlomanouy “Cis Ahoy remarks upon, a series of lantern-slides of the Foetus of a Three-toed Sloth (Bradypus tridactylus) ......... The Sucrerary. Report on the Additions to the Society’s Menagerie during the month of January, 1921 ...... Prof. G. Exrior Smiru, F.R.S., F.Z.8. Exhibition of, and remarks upon, photographs of a living example of Derrsigast i) (CE Naberlt eee 3 i. 0 lat Awe aed ara Dr. R. W. Suurevpt, C.M.Z.S. The last of the Passenger- Pigeons (Hetopistes migratorius). (Text-figure 1.) ... Mr: R. i, Pococx, ER.S; F.Z.S. Exhibition of, and remarks upon, the skull of a Sumatran Tiger ......... ——. Exhibition of, and remarks upon, a Cheetah skin Heo Ieynem aye, ALGierROI 55 oac0o-coppocebcEbocHaobaReseHe The Sucrerary. Report on the Additions to the Society’s Menagerie during the month of February, 1921 ...... Dr. P. Caaumers Mircusny, C.B.E., F.R.S. Exhibition of, and remarks upon, lantern-slides of a Baby Chim- panzee born in the New York Zoological Park ...... 183, 184 184 iv Sir Sipvey F. Harmer, K.B.E., F.R.S. Exhibition of, and remarks upon, a photograph of Elephant Twins ...... Mr. KE. G. Boutenerr, F.Z.8. Exhibition of Reptiles and Batrachiams |)" 1 1... 00k, Sh. een er, Miss L. KE. Cuyresman, F.E.S. Exhibition of, and remarks upon, a nest of Anapha venata (Lepidoptera) ......... The Secretary. Report on the Additions to the Society’s Menagerie during the month of March, 1921 ......... Mr. R. H. Burne, M.A., F.Z.S. Exhibition of, and remarks upon, a series of mounted specimens of young Flat Fish demonstrating various stages in the transference of the left eye to the right side of the head ............ Dr. P. Cuatmers MircHeu, C.B.E., F.R.8. On a letter received from Mr. EK. H. Bean, Director of the Wash- ington Park, Milwaukee, Wis., U.S.A., describing the successful rearing of a Polar Bear Cub ............ Mr. C. Davies Suerpory, F.Z.S. Exhibition of a coin of the Saka Dynasty, showing the so-called “ maneless INKCrai adi Aten oer rome ates atic Ee ere) Cala tbat ee Mr. F. Martin Duncay, F.Z.S. Exhibition of, and remarks upon, a series of lantern-slides of a remarkable nest of the Wasp (Vespa Germanic) 51.04) ...00s6 4000-0. 4acde- Mr. D. Sera-Suiry. Exhibition of, and remarks upon, a series of skins of the Australian Budgerigar (Melo- psittacus wndulatus), showing colour-varieties that have been produced) immcaiiviby. meee ere eaeeee rere Major E. E. Austen, D.8.0., F.Z.8. On an apparent change of habitat on the part of the Common Cricket. (Garalines| domesticus aan aerer CPR eee 443 443 443 444 444 445 445 o PAPERS. . The Comparative Anatomy of the Tongues of the Mammalia.—Il. Family 1. Simiide. By Carus F. Sonnrac, M.D., Ch.B., F.Z.S. (Anatomist to the Society) (lext—tieunes l= 95). usescseueesae. eeeeecse . Note on the Capture (in London) of a rare Parasitic Fly, Hammomyia (Hylephila) unilineata Zett. By Lt.-Col. S. Moncxron Copeman, F.R.S., M.D., F.Z.8. (Mexijsii@uee) Ils)” ipod she dodobonsenn soca ccosdobcagdsanabbecesce . The Bases of Classification of the Theriodontia. By D. M. 8. Watson, F.Z.S. (Text-figures 1-29.) ...... . Experiments on Colour-Changes of the Spotted Sala- mander (Salamandra maculosa), conducted in the Society’s Gardens. By E. G. Bounencrr, F.ZS, (Curator of Reptiles). (Plates I. & II.; Text- ATR S al US | LAI a en esi totic ep EE RP RR nA Scone Le . Contributions to the Morphology, Classification, and Zoo- geography of Indian Oligocheta. By J. SrEPHENSON, D.Sc., F.Z.S. (Lecturer in Zoology in the University of Edinburgh)ay (lext-fioure: 12) i jesse: ese. foes neces . On the Structure of the Reptilian Tarsus. By R. Broom, D.8c., F.R.S., C.M.Z.S. (Text-figures 1-27.) ......... . A Contribution to the Anatomy of the Three-toed Sloth (Bradypus tridactylus). By CHARLES F. SONNTAG, M.D., Ch.B., F.Z.S. (Anatomist to the Society). (Plates L.-1V.; Text-figuresel0—15.) ................-. . Report on the Deaths which occurred in the Zoological Gardens during 1920. By N.S. Lucas, M.B., F.Z.8. (Patholosisieto) then soctety,)\) seqsc-masesssssseeais< sae cass On the Reproductive Organs of the Ascidian Aviken- thalia borealis Gottschaldt. By Dr. Augusta ARNBACK- Crrignim- loin) GRext ie uresml--82)) a © & = of 2 Sy (Ue #2284 op Byte je = 2 p 1 Srl Gs 42 S Si a 4 a ee Fen ee aon it = eae: SC g Poe ts aa 2 G te (=) oer pS 5m A i) aa) aE es q i fas 3 = f S ® |—~ = Sp Ss: = . —~ ~ GQ eS =SS& F S Bit Ses 3S S| =o Obs BH > 4 = \S HAY) = Aly y is} ~ & / ~ is Me SS I~ q = \> 2 => > 7, Sie | S iS ZY R ok =) In the pro-otic on its front face, above, and in front of the fenestra lies the outer opening of the foramen for the facial nerve. This opens downwards and has below it a little hollow for the geniculate ganglion. Immediately above and a little in front of the facial is another much larger foramen opening directly forward ; its outer margin 48 MR. D. M. S. WATSON ON THE is carried by a spout-like projection from the pro-otic, its inner border is basisphenoid. That bone immediately in advance of the foramen has a deep depressed groove. There can be no doubt that this foramen is for the fifth nerve, the cavity before it having housed the Gasserian ganglion. Above and in front of this foramen the pro-otic is continued forward, having a suture with the basisphenoid, until its anterior margin or that of the in- distinguishably fused supraoccipital is cut into by a notch, which is very nearly converted into a foramen by the basisphenoid. This foramen must be venous; it is in part the homologue of one which is almost constantly represented in Therapsids. The supraoccipital is as always spread out into a wide plate, but from the anterior part of this expansion a special thickening Text-figure 9. Tap. QuJ, Qu. FrAr BOc B.Se Scynnognathus whaitsi Broom. R. 4053. B.M.N.H. Occipital aspect of skull, with the anterior ends of the proatlas attached. x #. PaR., parietal ; Qu., quadrate; T.B.Sp., tuber basi-sphenoidalis. is carried forward, forming the roof and part of the side-wall of the brain-case. It is this thickening whose margin forms the dorsal border of the venous notch. With the sides of the upper part of the supraoccipital in the region of this thickening the interparietal articulates, stretching far forward in contact with the parietal above and the supraoecipital below, and widely exposed in the outside view of the brain-case. The basisphenoid is a remarkable bone, which in the speci- men is broken off in front. As far as it is preserved, how- ever, it consists of a body which is articulated with the front of the basioccipital largely through the intermediary of the two 49 CLASSIFICATION OF THE THERIODONTIA. massive downward projections, which are its tubera. Above this articulation the bone becomes narrower where it is attached to the “SOATOU VSO} FO JIX9 OU} 1OF VUIUMBLOF,“ KX “TTA “A * ploytwopo “aQ { vAjUed1ezUT pug pux 4ST “O*T ‘sipwao vaqsouef “AQ'Na, { prousyds “OFIQAC =,“ plowuyya ,, “Ho + plosksojdide “uagyy ‘sxe “x YW £ Youe [anu [ejURyR “NP GY—: PALM “atozoq sv s19q 40] soUaIOFOXT ay} Fo [erpeut snl qno ezyW1Sesvavd vB \ \ O10 qi\vony \soG1/Hdd wa Ml NOY UWA NIA “UOTPISOd UI SIXY PUL SETIV TT] YYLM “essoz [vtodute,-qsod Aq peroutat St [[NYS oY} JO Vprs Jjoy olf} MoPA\ Was sv asvo-UIBIG OT} JO Joodsv [LI09VI 4JOrT 2X “SSOP Y mors [[M}YS pues sey “YW WO sty “Moog ispipydar snyjoubouuhag eee ea kee eK ray TANS AK AIRS \, 09 By) UF ‘Ol ONS y-4x97, onl 4 Its lateral face here bears the groove for the Gasserian ganglion, above which the bone again widens to the continuation Proc, Zoou. Soc.—1921, No, IV. pro-otie. 50 MR. D. M. S. WATSON ON THE of its suture with the pro-otic. Above and in front of the termination of this suture the basisphenoid is still continued upward as a slender process, whose upper margin is the lower border of the great venous notch and whose lower margin meets its fellow in an open median suture below the brain, immediately in advance of the hypophysis. The rostral part of the basi- sphenoid is a‘ vertically placed plate arising from the body of the bone and separated from the upper parts, just described, by a deep narrow notch, the open side of the pituitary fossa. From its sides arises the thick flat expansions, which are the basi- pterygoid processes. These incline downwards at the back at an angle of about 45°, and whilst their dorsal surface is sharply separated from the vertical face of the medial lamina, which lies above them, their ventral faces pass smoothly down to form a blunt ridge on the lower surface of this part of the basisphenoid. The parietal is composed of a plate of bone lying on the roof of the skull with an almost plane dorsal surface. Its postere-lateral corner is drawn out into a long process, which passes backwards to touch the extreme tip of the squamosal. The posterior edge of the whole bone is in contact with the interparietal towards the middle line and with the tabular laterally. By far the greater part of the outer margin of the parietal is in contact with the postorbital, which completely excludes it from participation in the margin of the temporal fossa. From the lower surface of the parietal a powerful ridge is developed, which marks the side-wall of the brain-case. Posteriorly this ridge just touches the anterior end of the supraoccipital. Immediately i in front of this bone it has a suture with the epipterygoid; further forward its lower edge is free, but gradually declines, until at or about the front end of the parietal it vanishes. The lower surfaces of the pre- parietal and frontals form the roof of the brain-case in this region, and the lower surface of the anterior part of the brain is supported by an ethmoid ossification. This is a thin hemi- eylindrical shell of bone with a rib along its ventral surface in the middle, which indicates that it rested on a deep median septum now broken away and lost. The posterior end of the ethmoidal cavity is widely open. The opening of the anterior end is much contracted and lies close up to the skull-roof. The floor of the cavity close to its anterior end is perforated by a pair of large oval foramina, which face downward. These are separated only by a narrow septum and must be for the optic nerves, which hence had a remarkably long intracranial course. The epipterygoid is only represented “bar its upper end, which, though narrow antero-posteriorly, is thin. It has a suture with the parietal and with the front end of the eee the latter connection being of considerable morphogenetic importance. There is a medium- “sized foramen for the Xth nerve, opening downwards and backwards below the exoccipital well above the CLASSIFICATION OF THE THERIODONTIA, 5] Text-figure 1]. ‘ Far.Oc, Scymnognathus whaitsi Broom. Posterior part from R., 4053. Snout reconstructed from a series of transverse sections of 49369 completed from R. 4052. Ectopterygoid region+detached area including the vomer R. 4053. g. B.Pr., basipterygoid process. 4% 52 MR. D. M. S. WATSON ON THE bottom of the skull. There isa single hypoglossal foramen in the usual position. Taken as a whole, it is obvious that the brain-cavity was very small in relation to the skull, and especially that the cerebral hemispheres were still of much less bulk than the cerebellum. At the same time the very great proportional length of that part of the brain which lies in front of the fifth nerve foreshadows the great cerebral development which occurred in later allied forms. The palate of Scymnognathus whaitsi is still not known as a whole, but the anterior part is very well shown in the sections of 49369, from a reconstruction made from which text-fig. 10 is mainly drawn, and in the solid in R, 4052. The pterygoidal flange and one transverse bone are preserved in position in R. 4053, and that individual retains a small fragment from the middle of the palate just in front of the anterior end of the long pterygo- parasphenoid bar. This fragment shows a pair of much raised ridges, which lie on the pterygoids and diverge outwards as they are traced forward. ‘These are covered with a shagreen of small teeth. Between these the palate is deeply grooved ; lateral to them it is depressed into deep hollows. The dorsal surface of the fragment bears a deep median keel. This fragment has been cut across by a tranverse cut, so that it now shows three sections. That at the back shows that the keel is formed by < single bone whose lower edge is received into a groove on the upper surface of the fused pterygoids, which meet below it. In the middle section this median bone has a deeply grooved lower edge, the two thin ridges which form the side-walls of this groove being received in slits in the pterygoids. These latter bones meet in a median suture on the palate and here bear the massive tooth-bearing ridges. On the front section the median bone is exposed on the palate, forming the roof of the median groove and separating the pterygoids. The median bone thus corresponds exactly in position and relations with the posterior median bone in Gorgonops and the back of the vomer in Diade- modon. The anterior part of the palate resembles that of Gor- gonops in the relation of the internarial bar to the palatine process of the premaxille and in its shape. Near its anterior end the internarial bar is a single bone with a convex dorsal surface from whicha ridge rises. This ridge, which is detached, apparently by fracture, extends upwards and backwards, obviously representing an ossification in the nasal septum. The lower surface has a low median ridge separating two well-defined grooves. As this bone is traced backward it gradually becomes narrower from side to side until in the region of the first molar tooth, where it is seen in section (text-fig. 12), it has become converted into a plate 35 mm. in depth and only two millimetres thick at the lower edge, where it is widest. The dorsal centimetre of this narrow septum is clasped between two Or CLASSIFICATION OF THE THERIODONTIA. 3 thin films of bone, whose outer surfaces. are in contact with another pair of similar slender processes. Even in this region the lower edge of the median bone still lies considerably dorsal of the tooth-bearing margin of the maxilla. In the next section, about 1 em. further back, the median plate is shallower, its dorsal margin being curved downwards. The two pairs of plates which support its upper edge are thicker, but still retain their same relations. The next slab has fortunately been split longitudinally and somewhat developed, so that it gives conclusive evidence that the lateral pair of processes described above are part of the Text-figure 12. Scymnognathus whaitsi Broom. Series of transverse sections at about 1 cm. interval, across the snout of No. 49369. B.M.N.H. 1, anterior section; I.N.B., internarial bar; in 2-5 only the internarial bar is represented ; in 6 the maxillee and palatines are shown ; in 7 only the anterior ends of the palatines and pterygoids. X 3. palatines. The inner pair pass down to the veritral surface and there form a little boss on the palate, which separates the two deep grooves on the palatines. These grooves are so overhung by the more ventral parts of the palatines that their floor can scarcely be seen in a direct ventral projection No sutures can 54 MR. D. M. 8S. WATSON ON THE be seen in the little median boss, and it is probable that the median element of the internarial bar has terminated in it. The vertically standing part of the palatine, which forms the side-wall of the groove just described, descends to the level of the lower border of the maxilla, where it passes into a flat, thick, horizontally lying plate, which extends outward to the lower edge of the maxilla with which it has a suture. This horizontal part of the palatine forms the greater part of that bone, and extends backward and forward in contact with the maxilla, until by narrowing and increasing in depth it becomes converted into a mainly vertically disposed plate, which forms part of the side-wall of the posterior part of the very large internal nares. It then terminates, Text-figure 13. Ds : ‘th Pe Scymnognathus whaitsi Broom. Reconstruction of internal aspect of the left side of the snout cut through in the middle line. Internarial bar and ossification in the nasal septum unshaded and surrounded by a thick continuous line; anterior end of the pterygoid represented by a line of sma]! crosses. Parts of palatine seen through other bones in broken line. Reconstructed from the sections of 49369, checked by R. 4052. & 3. Thus the angerior part of the palate is essentially a flat plate of bone, whose middle part is cut out by a narrow but gradually widening groove which plunges steeply downward to the deeply sunk posterior margin of the posterior nares. This groove is divided into two by a narrow vertical septum, which descends nearly to the level of the general plane of the palate. CLASSIFICATION OF THE THERIODON'TTA. By) There can be little doubt, especially when the conditions in Arctops and Gorgonops are considered, that the inner pair of pro- cesses which support the in teen ene bar are the anterior ends of the pterygoids. It remains to be shown by other material whether the median internarial bone and the median vomer in the back of the palate are parts of the same bone or are, as is more probable, separated. The strange way in which the median internarial bar rises as a thin but very deep septum from the much sunk posterior nares, nearly to the general level of the palate, seems to be only explicable if its ventral border supported the middle of a small soft secondary palate stretched between the maxille and the palatines. I have already described the mode of articulation of the squamosal with the brain-case and with the fused quadrate and quadrato-jugal in Proc. Zool. Soc. 1914, p. 1034, fig. 6. The squamosal above the level of the post-temporal fossa bows out backward, so as largely to increase the size of the dorsal opening of the temporal fossa. It thus makes the occiput very deeply cupped, the interparietal region being narrowed and the outer part of the tabular running nearly antero-posteriorly. At the extreme postero-lateral corner of the skull, the squamosal turns sharply into a process passing forward and inward in the zygomatic arch. This process is clasped by other bones both admesially and externally. One of these bones is the jugal. The other conceivably also jugal, but much more probably postorbital. A gap about 2 cm. long in both sides of the specimen prevents a definite decision on this point. The squamosal at the corner is made of a very peculiar, extremely dense, though finely cancellous bone. This structure is found in this region in all Theriodonts I have examined. LEPTOTRACHELUS EUPACHYGNATHUS, gen. et sp. nov. Type: a skull and lower jaw, described in error as Seymmo- gnathus whaitsr Da the writer (Ann. & Mag. Nat. Hist. ser. 8, vol. x. v ae fig. 3, and Proce. Zool. oe 1914, pp. 1027, 1032, figs. 3, & 5). The es is a largely disarticulated skull varying in preservation, with one complete and one partially disarticulated ramus of the lower jaw. The skull is represented by the brain- case, interorbital region, left nasal, lachrymal, prefrontal, jugal, and squamosal in natural articulation, the right jugal, lachrymal, and prefrontal in natural articulation, but separated from the skull, an isolated maxilla, and quadrate and quadrato-jugal. The mode of articulation of the quadyate with the sq uuamosal is clear, and with the perfect lower jaw gives the length of the skull and the position of the maxilla. The large articulated part of the skull gives practically all the dorsal and the posterior part of the lateral surface directly. The occiput is essentially 56 MR. D. M. 8. WATSON ON THE completely preserved. All the sutures except those of the parietals with each other and the preparietal are well shown. In text-fig. 14 it is probable that the anterior part of the snout is made a little too narrow. I have already described and figured the basicranial and otic regions, the occiput, and the interior of the brain-case. on} Text-figure 14. Se ees een Leptotrachelus eupachygnathus, gen. et sp.nov. Type-skull. Dorsal aspect. X 2. The outside of the brain-case is illustrated in text-fig. 16. The foramen for the V1Ith nerve lies just above and in front of the fenestra ovalis, opening downwards through the pro-otic. The CLASSIFICATION OF THE THERTODONTIA. 57 trigeminal “foramen” lies considerably forward and is more dorsal in position. It les at the end of a long slit and is pre- sumably really only an incision and not a foramen, The length Text-figure 15, Fi cleeait at IE ———— ee ——— —— Tana Leptotrachelus eupachygnathus. 'Type-skull. Right lateral aspect. XX 3 Text-figure 16. SSS SS i i e-+e--5 SSS _-- ForVi PBR Vil Fen.Ov. BOc. Leptotrachelus eupachygnathus. Type-skull. Lett lateral aspect of brain-case, the parts of the skull lateral to the post-temporal fossa being removed as in text-fig. 10. of the slit is rendered uncertain by the fracture of the anterior end of this part of the brain-case. In the part of the brain-case preserved there is no evidence of the large venous foramen 58 MR. D. M. 8S. WATSON ON THE described above in Scymnognathus whaitsi. There is no trace of the great anterior projections of the basisphenoid which in Scymnognathus meet in median suture in advance of the pituitary. There is an ethmoid, which, so far as its very imcomplete exposure allows it to be seen, does not differ from that of Scymnognathus. The squamosal of Leptotrachelus is remarkable for the great length of its lateral projeetion and the extreme suddenness of the postero-lateral corner. As in Seyninognathus its distal end is received between two bones, here almost certainly the jugal and postorbital. The cup-shaped depression in the widened lower edge of the squamosal into which the head of the quadrate fits is very narrow, not half the width of the projection of the squamosal. The quadrate is a relatively large bone about 30 mm. high by 15 mm. wide; it forms a nearly parallel straight-sided figure, the lower edge e being a little marked off by a groove and forming the articular: are The upper end is rounded and fits snugly into the hollow in the squamosal. The quadrato-jugal is fused with the articular margin of the quadrate; it then separates from that bone, leaving a small quadiate foramen, whilst. farther dorsally it spreads out into a flat sheet of bone which covers the outer margin of the quadrate and laps over its posterior surface. When articulated with the squamosal the quadrate and quadrato-jugal are largely visible from behind. The maxilla of ZLeptotrachelus shows a single canine in use, with traces of the crown of a successional canine high up in the alveolus, and four cheek-teeth ; it is possible that there was really a fifth cheek-tooth. LycosaURUS PARDALIS Owen, Cat. Foss. Rept. 1876, p. 15, pl. 14. The type-skull of Lycosaurus pardalis was re-examined and discussed by Broom, Proc. Zool. Soe. 1911-12, p. 1079, who gave it a dental formula: 1. 5, ¢. 2, m. 4. The type-skull (R. 1717, B.M.N.H.) from the Cistecephalus- zone (%) of the Sneeuberg is considerably crushed laterally, but has the anterior end of its snout complete and well-preserved ; behind the canine on the left side the outer surface of the skull is complete to the orbit, the whole orbital margin is present and a bit of the edge of the parietal region. The other side is a weathered face which cuts further and further mto the skull until it so far crosses the middle line as to expose the admedian surface of the left epipterygoid and completely to remove the brain-case. The squamosals are completely destroyed. The right lower jaw is, however, nearly perfect, having suffered only the loss of the posterior part of the angular so as to expose the articular—the position of the quadrate is thus fixed. The parts of the skull remaining are quite well-preserved and show many sutures, CLASSIFICATION OF THE THERIODONTIA. 59 It is obvious that the snout is short, high, and narrow, with no trace of the square section which occurs in all the Gorgonopsids described above. The tooth-bearing edge of the maxilla is curved and passes gently into that of the premaxilla without the step of Gorgonops 7 y . . ; or Scymnognathus. here is, however, a diastema between the closely-set incisors and the canine. There are clearly 5 incisors, | canine, and 4 or possibly 5 molar teeth. The small canine recorded by Broom immediately in front of the large one does not exist on the well-preserved left side, and his views seem to have been founded on a small strip of tooth in this position on the right side, which is really an exposed portion of the lower canine. The maxilla is short and deep. Text-figure 17. al ) f Lycosaurus pardalis Owen. Type-skull. Reconstruction of the right lateral aspect, X 3. The parts represented in broken lines hypothetically restored. The external nostril of Zycosaurus differs considerably from that of Gorgonops. It faces more laterally and is much larger ; it is no longer overhung by so large a corner of the nasal, although there is still a trace of the older structure. The facial part of the septomaxilla is much smaller, and the foramen between that bone and the maxilla is not only smaller but opens more directly outward. The septomaxilla in front of it seems to be rounded and grooved. Finally, the internarial process of the premaxilla is longer and stands more vertically, so that the end of the snout is deeper and less rounded in side-view. The interorbital region is narrow, the postfrontal being a narrow pointed strip, as in the skull of Arctognathus curvi- 60 MR. D. M. 8S. WATSON ON THE mola subsequently described (text-fig. 18). The parietal region is obviously of the Gorgonopsid type and cannot be very wide, although its width cannot be determined with any pretence to accuracy. ARCTOGNATHUS CURVIMOLA (Owen), Cat. Foss. Rept. 1876, p. 71, pl. 68. The skull (No, 47339 B.M.N.H.) described by Owen as Lyco- saurus curvimola was found with Dicynodon tigriceps in the Cistecephalus beds of the Kagaberg, near Bedford, S. Africa. Its palate was developed by Mr. Hall and described by Prof. Seeley, Phil. Trans. B. 185. The skull was then examined by Dr. Broom, who noted that the parietal region seemed to be broad, and made for it the genus Arectognathus. The actual preservation of this skull is good; but before it was buried the left maxilla and ectopterygoid, together with the bit of lower jaw in their vicinity, were separated from the rest of the head by a nearly plane split, moved outwards for about 15 mm. and there fixed in the sediment. How this very peculiar result was brought about is very difficult to understand, although tentative suggestions might be made. Whilst lying at the surface the nodule containing the skull was exposed to weathering, which has cut down into it so as completely to remove the right squamosal, the parietal region beyond the middle line, and the postorbital bar. Fracture has removed the occipital condyle and part of the paroccipital process, but has left the stapes and quadrate with the lower jaw in articulation on the right side. Enough of aa occiput is left to make the structure clear. The palate is wel exposed and very well preserved, the right ramus of the mandible is perfect and weli-exposed. On the dorsal surface of the parietal region the suture between the parietals and the pineal foramen are very well shown on a weathered face, which lies a little below the original dorsal surface; the right side of this region retains its natural surface and shows the structure clearly. The skull is short, broad, and deep. The snout is rounded in section and terminates in front in the internarial premaxillary processes, which form the extreme front end of the skull over- hanging the oral margin. The very large nostril faces largely outward and is not over- hung by an outstanding corner of the nasal. The septomaxilla is small, and the foramen between it and the maxilla very small. The interorbital width is considerable, but the orbits look upward and forward as largely as outward. The frontal does enter into the orbital margin, but only through a short distance The postfrontal is a narrow strip of bone wedged in between the frontal and the postorbital. No trace of a preparietal is to be seen on the parts preserved, CLASSIFICATION OF THE THERIODONTIA. 61 the median suture is clearly shown from the front of the pineal foramen to a point between the frontals, and the well-marked suture between the frontal and parietal passes very little in advance of the pineal opening. These sutures are, however, exposed at a plane below the orginal dorsal surface, and there is a remote possibility which cannot, although very improbable, be entirely excluded, that the pvreparietal was represented by a Text-figure 18. Arctognathus curvimola Owen. ‘Type-skull, Restoration of the dorsal aspect, the parts in broken lines being hypothetically restored. minute scale of bone lying on the dorsal surface. The parietal region is about as wide as the interorbital. The maxilla is short and deep, its tooth-bearing margin 1s much curved and passes smoothly with no trace of a step into that of the premayilla. The canines appear not to be completely erupted, and the four small cheek-teeth are also not very firmly 62 MR. D. M. 8S. WATSON ON THE planted. The four incisors, though powerful, are not so dispro- portionately large as they are in earlier Gorgonopsids. The palate of Arctognathus is very well-preserved, but its anterior end and two strips along the maxille are concealed by unremoved matrix and by the lower jaw. The basioccipital is broken off through the vagal foramen, where it is thin and not very wide. The posterior part of the Text-figure 19. cn Se Arctognathus curvimola (Owen). 'Type-skull. The palate, X 3. Stippled area covered by matrix and the lower jaw. Parts in dotted lines hypothetical. Ais cane A, direction of the section of ‘‘ Lycosaurus tigrinus,” text-fig. 20. St., stapes. basisphenoid forms a triangular area with raised lateral margins, representing the tubera of earlier forms. Above the edges the sides of the bone are flat and vertical, posteriorly they terminate in the region of the fenestre ovales, these openings being con- cealed by the foot of the stapes. Anteriorly these vertical sides of the basisphenoid approach together until they are only CLASSIFICATION OF THE THERIODONTIA,. 63 separated by a narrow ridge which runs forward to the palate proper. From the vertical sides of the basisphenoid horizontal processes arise; these basipterygoid processes support the ptery- goids. From their articulation with the basisphenoids the pterygoids pass backward towards the quadrates, but do not articulate with those bones, as they appear to terminate in free points before reaching them. ‘The pterygoids pass forward, forming with the median ridge which continues the basisphenoid a bar whose ventral surface is almost cylindrical, broken only by the median fillet. At the hinder end of the palate the pterygoids suddenly widen, forming very deep powerful flanges. This part of the bone has a transverse suture with the ectopterygoid. Medially the two pterygoids meet in a visible suture which lies at the bottom of a small depression. ‘his suture soon terminates at the brim of a much deeper and more sharply-marked hollow, which, as it passes forward, widens and is converted into a deep open groove forming anteriorly the whole roof of the much vaulted palate. Throughout its extent this groove has well-marked, indeed often vertical, sides. Anteriorly this groove is divided into two by a ridge which rises from its surface. At about the level of the last maxillary tooth this groove is bounded by roughened areas of bone, which appear to have borne teeth. These areas are undoubtedly on the pterygoids and are separated by visible sutures from the palatines, which he laterally to the pterygoids in front of the ectopterygoids. Further forward these sutures, which form the inner border of the palatines, approach one another and descend into the groove, so that its side-walls are in front formed by the palatine. The ectopterygoids are separated from the palatines by visible sutures. There is no trace of a suture down the mid-line of the groove, and its roof seems to be formed by a median bone, which terminates at the sudden end of the groove and must be bounded by sutures with the pterygoids along its edges; of these presumed sutures nothing can be seen in this specimen. The type-specimen of Lycosaurus tigrinus Owen seems to throw light on the structure of the palate of Arctognathus curvimola. It consists of a fragment of a snout, broken off through the premaxillee in front and by an oblique fracture on the left. side, but showing much of the right maxilla. It has been so developed as to show a small strip of the surface of the right palatine and shows a section of the palate on the hinder end. This species is referred by Broom to a new genus Arctosuchus, and said to have a dental formula, 1.5, c. 1, m. 4 or 5, representing a much more primitive type of Theriodont than