290 Bulletin American Museum of Natural History. [Vol. XVI, 



PDinocyon (Borophagus) diversidens (Cope). 



Borophagus diversidens Cope, Amer. Nat., 1892, 1028; Vert. Pal. 

 Llano Estac. (4th Ann. Rep. Geol. Surv. Tex., 1892), 54, pi. xiii, fig. 4. 



Blanco horizon (Upper Pliocene). Referred to the Hyae- 

 nidae by Professor Cope. The type is a fragment of a lower 

 jaw, with two premolars preserved and the root of a third. It 

 agrees with Amphicyon more nearly than with Hycena in the 

 form of the individual teeth, as well as in their proportion one 

 to another; the second premolar is smaller, apparently, than 

 in the Loup Fork species. 



? Dinocyon (? Borophagus) gidleyi Matthew. 



Dinocyon (? Borophagus) gidleyi Matthew, Bull. Am. Mus. Nat. 

 Hist., Vol. XVI, 1902, 129-136. 



? Amphicyon ursinus Cope. 



Canis ursinus Cope, Proc. Phila. Acad. Nat. Sci. 1875, 275; Rep. 

 Wheeler Survey, Vol. IV, pi. ii, p. 304, pi. Ixix, fig. i. 



The reduction of the premolars, proportionately large tu- 

 bercular teeth, deep, massive jaw with comparatively straight 

 inferior margin, large heel on the lower sectorial, etc., place 

 this species with the Amphicyons. Professor Cope remarks 

 on the probability that C. ursinus is very close to C. haydeni. 

 Leidy's species is, however, much more like the wolf in pro- 

 portion of sectorial to tubercular teeth, and the heel of the 

 sectorial is comparatively small, as in C. lupus or in the 

 .^lurodons. 



A. ursinus is about the size of .4. americanus , and is perhaps 

 synonymous with it. 



