THE ARTIODACTYL UNGULATES 207 



origin, the earliest fossil remains dating back no further than 

 the Miocene. 



As an example of the Cervicornia we take the black-tailed 

 Virginia deer, Odocoilens hemionus (Fig. 74), a genus which 

 has changed very little since Pliocene times. The skull is that 

 of a young doe but shows by the relative wearing of the teeth 

 how much later than the first the third molar erupted. The 

 dental formula is: 



if, Cy,p^M|. total 32. 

 Of the lower incisors, which Avith the incisiform canines* are 



Fig. 74. — Dentition of Black-tailed Virginia Deer (Odocoileus hemionus, 9.7351-7). 

 In this example of Ruminant dentition can be observed in more pronounced degree the 

 features already noted in the Camel. The specimen is a young one and still retains in 

 front of the permanent molars the three milk molars which precede the premolars. The 

 lower permanent canines are lost. 



procumbent, the median pair is much the largest. No trace of 

 the upper canines exists. There is a considerable interval be- 

 tween the incisors and the cheek teeth, the maxillary series of 



*The canines are lost in the specimen figured. 



