I 12 Bulletin Avierican Museum of Natural History. [Vol. XII, 



crown of the fourth premolar has a prominent submedian cutting 

 heel. The length of the lower dental series from the alveolus of 

 the first premolar is 41 mm. 



Uintacyon canavus ' {Cope). 



This species is represented by the jaws of four individuals in 

 the collection, all from the Wind River beds [Nos. 4783 (type), 

 4784, 4786, 4798]. The type consists of a lower jaw bearing the 

 first premolar, but displaying the roots of all the remaining teeth. 

 In the other specimens the crowns of the other teeth are moder- 

 ately well preserved, so that the lower dentition can be determined. 



As compared with the preceding species, the jaw is not quite 

 so deep and heavy, especially in the region of the symphysis, the 

 anterior premolars are smaller and more spaced, and the fourth 

 much more reduced than in the preceding species. Two of the 

 specimens show the alveolus for the last molar, and Indicate that 

 this tooth was implanted by two distinct roots, whereas in the 

 preceding species the alveolus is not divided. 



In this connection it is proper to mention a specimen from the 

 Wind River, consisting of the last two molars (No. 84), which does 

 not agree with either of the Wind River species, U. canavus and 

 U. brevirostris, in that the last molar is single-rooted, as it is in 

 the Wasatch U. promicrodon. The premolars belonging to this 

 type are entirely unknown, and it would not be at all surprising 

 if another species is indicated by this specimen. If the anterior 

 premolars are reduced, it undoubtedly represents the direct suc- 

 cessor of U. proniicrodon in the Wind River. Until better 

 specimens are known, we refrain from proposing another specific 

 name. 



The entire length of the lower molar series of the present 

 species as indicated by the type is 42 mm. 



Uintacyon brevirostris'' {Cope). 



The type of this species consists of a lower jaw (No. 4785) 

 from the Wind River beds ; it is the only specimen known from 

 this horizon. The jaw is short and deep, as in the preceding 

 species, and the canine is laterally compressed. The premolars, 



' Bull. U. S. Geolog. Surv. Terr. VI, Feb. 1881, 186. 

 2 Bull. U. S. Geolog. Surv. Terr. VI, Feb. 1881, 190. 



