1913] Merriam: Notes on the Canid Genus Tephrocyon 371 



to difference in wear. It will be necessary to have more material, 

 and especially to secure a specimen with M 2 , before the exact 

 relationship of this form can be determined. 



A portion of a mandible with Mj and P 4 (12504) from the 

 Middle Miocene of High Rock Canyon, Humboldt County, Nev- 

 ada, represents a species larger than that from Little High Rock 

 Canyon. P 4 differs from that of Tephrocyon rurestris in the 

 possession of an anterior cusp. The entoconid of the heel of Mj 

 is relatively smaller than in the specimen from Little High Rock 

 Canyon. In several characters this specimen resembles T, hippo- 

 phagus more nearly than it does T. rurestris, but it is probably 

 distinct from both species. 



Although the specimens from the High Rock and Little High 

 Rock beds resemble the typical Tephrocyon, in many respects 

 they are quite different from T. kelloggi, and future study of 

 this group of canids may show that the fragmentary forms last 

 described are separable at least by subgeneric characters from 

 the T. kelloggi type. 



Matthew and Cook 5 have compared fragmentary material 

 from the Snake Creek Beds to Can is vafev Leidy, and have ten- 

 tatively referred this form to Tephrocyon. It seems to the writer 

 doubtful whether Canis vafer can be included in the same generic 

 group with Tephrocyon rurestris and T. hippophagus. 



Relationships op Tephrocyon 



Writers who have expressed an opinion on the affinities of 

 Tephrocyon have considered this group as distinguished by char- 

 acters in some respects like those of Canis, and in some particu- 

 lars like those of Aeiurodon. The further study of the group 

 bears out these assumptions, and future work may show that 

 both Canis and Aeluroelon are derivatives of the Tephrocyon type. 

 Later study will probably reveal many varieties of the Tephro- 

 cyon group as yet unknown, some of which will be more like 



5 Matthew, W. D., and Cook, Ii. J., Bull. Am. Mus. Nat, Hist., vol. 26, 

 p. 376, 1909. 



« Merriam, J. C, op. cit., 1906. 



Matthew, W. D., and Cook, H. J., op. cit., 1909. 



