266 



University of California Publications. 



[Geology 



proach Equus. Relationship to Neohipparion can not be dis- 

 proved, as the protocone region is not preserved in any of the 

 specimens. The presence of a number of large, heavy astragali 

 of the Equus type in the Thousand Creek region lends some sup- 

 port to the view that the large molar teeth represent that genus. 

 It is also possible that these forms represent an Equus derived 

 from a terrace formation of Pleistocene age which has possibly 

 been laid down over the Thousand Creek Beds. In some of the 

 localities at which these specimens were found there is distinct 

 evidence of terracing, but no deposits have been recognized which 

 are distinguishable from the Thousand Creek Beds into which 

 the terraces are cut. 



Numerous scattered remains of rhinoceroses were found both 

 at Virgin Valley and at Thousand Creek. The specimens consist 

 mainly of loose foot-bones, with a few teeth and parts of jaws. 

 None of the specimens seem to the writer to be definitely deter- 

 minable. 



A last upper molar and a portion of a lower jaw with the 

 dentition (figs. 37 and 38), and several astragali from Virgin 

 Valley are tentatively referred to Aphelops. 



Fig. 37. Aphelops ( ?) , sp. Fragment of inferior mandible with den- 

 tition. No. 11607, X Virgin Valley Beds, Virgin Valley, Nevada. 



Fig. 38. Aphelops{1), sp. M 3 . No. 11672, X %. Virgin Valley Beds, 

 Virgin Valley, Nevada. 



RHINOCEROTIDAE 



APHELOPS ( ?), sp. 



38 



