1326 CLASS MAMMALIA. 



has a descending flange. Some writers include this -family in the 

 Aitthracotheriidce, and perhaps this is really the better arrangement. 

 The type genus is found only in the Pliocene Siwaliks of India 

 and Burma, where it is represented by M. dissimilis (fig. 1200), 

 and two smaller species. An imperfectly known but closely allied 

 form from the Upper Miocene of Sind has been described under 

 the name of Hemimeryx. In this and all the preceding families the 

 odontoid process of the axis vertebra is peg-shaped. 



Family Cotylopid^e. — This extinct North American family, 

 usually known as the Oreodontidce} is regarded by Professor Cope 

 as related to the AnoplotheriidcB, but with more completely seleno- 

 dont teeth and less specialised feet, which are more like those of 

 the Hippopotamus than those of the Ruminants ; but their affinities 

 are probably widely spread. Upper incisors are present ; the true 

 molars (fig. 1201) are selenodont, and those of the upper jaw 

 usually have only four columns on their crowns ; and the pre- 



Fig. 1201. — Oral surface of the right upper cheek-teeth of Eporeodon major. 

 Miocene, North America. 



molars are simpler than the true molars, but are not secant. The 

 lower canine is approximated to the incisors, and its function is 

 taken by the first premolar, which has a tall crown biting behind 

 the upper canine. The ulna, radius, tibia, fibula, metapodials, 

 navicular, and cuboid are all distinct ; and each foot carries four 

 digits. The odontoid process of the axis vertebra is intermediate 

 in shape between the peg of the Bunodonts and the half-cylinder of 

 the Ruminants ; the lachrymal bone frequently has a deep larmial 

 depression ; but the angle of the mandible has no descending flange. 



5 1 



In the type genus Cotylops (Oreodon) the dentition is I. -, C. -, 



Pm. -, M. -• the orbits are completely surrounded by bone, the 



premaxillse are separate, the auditory bullae not inflated ; there are 

 no vacuities in the bones of the face ; and there is a small pollex in 



1 The name Oreodon being preoccupied by Orodus {supra, p. 940), involves 

 the change of the family name. Cotylops was originally applied by Leidy to one 

 species of the type genus. 



