AMERICAN RUMINANT-LIKE MAMMALS. 255 



Camelomeryx is another genus which differs only in minor 

 details from Leptoreodon and which seems to be either the 

 ancestor of Leptomeryx or very near to that ancestor. In the 

 dentition of the White River genus we found reason to think 

 that it had been derived from some form in which the first 

 lower premolar functioned as a canine, and this condition, with 

 many others, is fulfilled in Camelomeryx, which is quite a small 

 and delicately built animal. 



The Uinta ancestor of Hypertragulus cannot yet be deter- 

 mined, because of the possible genera none are sufficiently 

 well known. The genus Leptotragulus seems, at the present 

 writing, to be the most likely candidate, but Oromeryx, or even 

 Bunomeryx, may prove to be the chosen one. 



The forerunner of the White River Oreodon has long been 

 known and has received the suggestive name of Protoreodon, 

 which expresses the ancestral relation. Protoreodon is, to all 

 intents and purposes, an oreodont, but it has several most 

 interesting resemblances to the agriochoeres, such as the open 

 orbits, the absence of the lachrymal pit, the elongate cranium, 

 and the pattern of the lower molars. The upper molars have 

 the fifth, or unpaired, cusp in the anterior half of the crown, 

 as Schlosser predicted would be found a prediction made 

 before the pre'sent genus was known. The skeleton is not 

 sufficiently different from that of its White River successor 

 to require any description. This genus shows us that the 

 oreodont family had become segregated as a distinct group in the 

 Uinta, but the very many likenesses of Leptoreodon to Proto- 

 reodon, on the one hand, and to Protylopus on the other, afford 

 the strongest confirmation to the opinion of Riitimeyer and 

 Schlosser that the oreodonts are a branch of the Tylopoda. 



What I believe to be the ancestor of Agriochcerus is a Uinta 

 genus as yet undescribed, which I propose to name Protagrio- 

 chcems. The only known specimen of this most interesting 

 form belongs to the American Museum of Natural History, 

 and for the opportunity of making a study of it I am indebted 

 to the kindness of Morris K. Jesup, Esq., President. It is, 

 unfortunately, very fragmentary, and hence indecisive upon 

 certain important points, but it is, nevertheless, exceedingly 



