7 



But the genus which associates more definitely the orders Carnivora 

 and Quadrumana, is the Cercoleptes, which F. Cuvier* placed between 

 the two. Its two cutting premolars and three true molars, with the co- 

 ossified rami of the mandible are truly Quadrumanous features, although 

 it should on other grounds be regarded as a plantigrade carnivore. Sev- 

 eral of the extinct genera of the Wyoming Eocene will prove to be allied 

 to this form. 



Cercoleptes does not, however, present us with the ultimate original type 

 of the Oamivora. Such a type must also generalize the seals, with their 

 longitudinal, cone-bearing molars, and fiat, fissured claws. Some of the 

 seals also unite the scaphoid and lunar bones later in life than other 

 Carnivora, hence we would reasonably look for the division of these 

 bones in their predecessors. The flat-clawed genera of Wyomingf answer 

 these demands. The genera Mesonyx and Synoplotherium presents us 

 with a series of molar teeth which repeat each other in form, are com- 

 pressed below, and bear conical cusps. The jaws in the latter genus are 

 slender, and the canines tend to the great development seen in many seals; 

 but principally, the scaphoid and lunar bones are distinct, and the claws 

 flat and widely fissured. The tympanic bone is more like that of the 

 bear, and some seals, than that of the digitigrade Carnivora. These 

 genera, though probably good swimmers, were well removed from the 

 seals in the structure of the long bones of the limbs, and were probably 

 remote in their ancestry. 



In Oligotomus, Orotherium, Hyopsodus and similar forms, the conic tu- 

 bercles of the lower molars have a slight alternation, and the posterior, 

 which has a crescentoid section in wearing, inclines to connection with 

 both the inner conic tubercles by low ridges. These ridges are fully devel- 

 oped m Palceosyops so that we have a dental crest of two Vs, in the infe- 

 rior molars. This in wearing produces the two crescents of Pakeotherium. 

 The addition of two tubercles on the inner side takes place in the higher 

 forms, which terminates in the four crescent-bearing molars of the Rumi- 

 nants. How this is done is proven later by examples from the maxillary 

 teeth. In Orotherium nasacciense there is a tendency for the conic tuber- 

 cles to be connected in pairs by low cross ridges. These ridges fully de- 

 veloped produce the two cross-crests of Ilyrachyus and Tapirus. In Rhi- 

 nocerus the outer portion retains a crescentoid form, giving rise to an 

 L-shaped crest. In Bathmodon diagonal ridges appear which would result 

 in two Vs, as in Palceosyops, were it not that both transverse and oblique 

 elements of the posterior V disappear, leaving but one such in the middle 

 and posterior part of the mandibular series. In JJintatlierium the diag 

 onal from the posterior crest never appears, leaving a transverse crest 

 and a V on the true molars. 



In the superior molar series the flattening of the outer tubercles may 



* Dentes des Mammifers, p. 31. 



t See the Flat-clawed Carnivora of Wyoming, by E. D. Cope, April, 1873. 



