GEOLOGICAL SURVEY OF THE TEEEITOEIES. 351 



all two-rooted, and form an uninterrupted series. The basis of the malar 

 part of the zygomatic arch originates opposite the adjacent parts of the 

 penultimate and last molars. The premaxillary bone is massive, and 

 with but little area for attachment with its fellow in front. The incisor 

 teeth are large, with subcylindric roots, and their alveoli are well sep- 

 arated. In one, perhaps superior, the crown is expanded transversely, 

 with convex cutting edge. 



In the humerus the deltoid hook is developed, but is not much ele- 

 vated above .the plane of the head. It originates from an external 

 expansion of the head, which bears a shallow cotylus separated from the 

 head by a low, curved, subtransverse ridge. The condyles of the humerus 

 do not support any trochlear ridges. An almost perfect femur of B. 

 radians is preserved- The third trochanter is not very prominent. The 

 little trochanter is little developed. The great trochanter is large but 

 does not equal the head. The latter is subglobular, and the ligament- 

 ous fossa extends to its rim. The distal trochlear surface is i^rominent, 

 the inner edge more so than the outer. Its articular surface is broadly 

 continuous with those of the condyles; a slight emargination of the out- 

 lines only marking the usual constriction on each side. In this it 

 resembles Cermdce and some Antilojjida;. The inner condyloid surface 

 is cut off by the emargination in Toxodon and Bos hiibalus ; the emargin- 

 ations are deep, but do not cut off either in JEquus, Gamelopardalis, and 

 three species of Bos ; while they are so deep as to cut off" both in Rhi- 

 noceros, 5 species — Sippojpotamus, Bos hrachycerus, B. sondaicus, and in 

 Catohlepas. 



A portion of the co-ossified parietals shows that the superior borders 

 of the temporal fossse were separated by a iiat plane, as in the hog 'and 

 other ungulates. 



Bathmodon radians. Cope. 



Proc. Amer. Pliilos. Soc, loc. cit. 



Eepresented by portions of several individuals, which indicate an 

 animal varying from the size of the ox to that of the Javan rhinoceros. 



The transverse diameter of all the molars exceeds their longitudinal. 

 In the penultimate, which may serve as a type, the superior or outer 

 plane of the inner crescent ridge extends along about .66 of the posterior 

 of the outer crescent. In the last molar this surface is very wide on the 

 posterior and inner side of the external crescent ; it then contracts and 

 expands again on the posterior side, its outer bopnding crest reaching 

 to the external margin of the crown. 



Besides these points, the molars possess a strong cingulum along the 

 anterior base of the crown, which unites with the surface near the inner 

 protuberance of the latter in the penultimate; in the last molar it 

 reappears, forming a short lobe on the posterior face. The enamel 

 where not worn is slightly rugose. 



A posterior premolar has a cingulum on the inner obtuse apex. The 

 crest of the inner crescent, descending on each side of the apex of the 

 outer, forms a cingulum-like ledge at its base as far as the angle formed 

 by the descent of the apex of the outer crescent. The outline of the 

 corner of this tooth, viewed from above, is narrow cordate, with obtuse 

 apex. The convexity of the outer crescent inward is very strong, and 

 the base of the crown is externally two-lobed. Enamel striate rugose. 

 In a more anterior premolar (with three roots) there is no internal cin- 

 gulum, and the crest of the inner crescent is not carried to the external 

 basis of the tooth, and is entirely wanting on the posterior face of the 



