Vol. 6] Merriam: Virgin Valley and Thousand ('reek. 241 



T EPHKOCYON ( ) , sp. a. 



The jaw fragment do. 12504 from Bigh Rock Canon (figs. 

 9a and 9&) represents a form not differing greatly from the 

 specimen tentatively referred to '/'. rurestris. The teeth on this 

 specimen are somewhat larger than in the type of T. rurestris; 

 P 4 is somewhat thinner and possesses an anterior basal tubercle ; 

 and the tubercles on the heel of M 1 are quite uneven in size, the 

 entoconid being considerably smaller than the hypoconid. 



There may be some doubt as to whether this specimen actu- 

 ally represents the genus Tephrocyon. In so far as it differs 

 from Tephrocyon it approaches the dogs of the Canis type. 



Measurements 



P 4 , anteroposterior diameter 12.7 mm. 



P 4 , transverse diameter 5.6 



M„ anteroposterior diameter 24.2 



M,, anteroposterior diameter of heel 6.4 



M„ transverse diameter of heel 8.4 



Height of mandible below protocone of 25. 



AELURODON ( ? ) , sp. 



A fragment of a large jaw (no. 12545) from High Rock 

 Canon (fig. 10) represents a form certainly quite different from 

 any of the species mentioned above. The jaw is very short and 

 massive. The dental series includes three molars and at least 

 three premolars, though the alveoli of the anterior premolars 

 are not clearly shown. The inferior carnassial has about the 

 same anteroposterior diameter as in specimen 12504 referred to 

 tentatively as Tephrocyon ( ?) , sp. a, but the relation of the dimen- 

 sions of this tooth to those of the jaw are entirely different. This 

 specimen evidently represents a type generically different from 

 the forms referred to Tephrocyon. The short massive mandible 

 suggests Aelurodoh, though the teeth seem to be relatively small 

 and weak for any of the species thus far described in that genus. 



Occurrence: Virgin Valley Formation, High Rock Canon, 



Humboldt County, Nevada. 



Measurements 



Height of mandible below protoeonid of M, 39. mm. 



Thickness of mandible below protoeonid of M 1 12. 



M„ approximate anteroposterior diameter 25. 



