620 The Phylogeny of the Camehde. [July, 
adherent to the sides of the two median metapodials. The infe- 
rior premolars in this genus are all much compressed, but differ 
much in form from those of Stibarus. The first upper premolar 
is a simple tooth with a subconical crown, totally different from 
the long cutting crown of the corresponding tooth in Poébro- 
therium. The next two premolars alone are compressed, though 
the third is rather wide posteriorly. The fourth is like that of 
other ruminants, 
The oldest species of Protolabis, P. transmontanus Cope (Fig. 
11), was obtained from the Ticholeptus beds, which overlie the 
John Day beds in Central Oregon. Its skull and a few bones 
Pa! 
t 
” 
Fic. 11.—Protolabis transmontanus Cope, skull one-third nat. size, from Ticho- 
leptus bed of Oregon. Fig. a, from left side; 4, from below. Original. z 
only are known, but the former displays very complete dentition. 
Its size is about that of the Virginia deer. , Its dimensions are w 
strict accord with the rate of increase of size to be observed in 
this series, and which it will be noticed, is maintained to the Plio- 
cene epoch, when the greatest dimensions were attained. i 
species of Protolabis appear in the succeeding or Loup For 
epoch which exceed the P, zransmontanus in size. These are the 
~ Vary in size from that of a sheep, as P. gracilis Leidy, to that = 
deer, P, occidentalis Leidy, and to that of a camel, P, 70H 
