Vol. 6] Merriam: Virgin Valley and Thousand Creek. 



257 



Ungulata 



EQUIDAE 



Remains of horses are among the most common fossils at both 

 Virgin Valley and Thousand Creek. In the small collection of 

 fragmentary material obtained by Mr. Smith and the writer in 

 1906 Mr. Gidley 14 found at least five species represented. The 

 material obtained during the past season unfortunately consists 

 only of scattered teeth and limb bones. It is, however, sufficient 

 to add considerably to what has been known regarding this 

 group. 



The forms present represent the genera Hypohippus, Para- 

 hippus, Merychippus, PMohipptis(l), and possibly Equus. 



An examination of the collection according to localities shows 

 that Hypohippus, Parahippus and Merychippus are found only 

 in the Virgin Valley Beds, and do not appear at all in the 

 deposits at Thousand Creek, while Pliohippusil) and Equus 

 are found at Thousand Creek and not in Virgin Valley. 



HYPOHIPPUS, near OSBORNI Gidley 



There is a considerable number of specimens of teeth and 

 limb-bones which are to be referred to this genus. The specific 

 characters, so far as determinable, represent a form combining 

 to some extent the characters of Hypohippus equinus of the Deep 

 River Beds of Montana and H. osborni from the Pawnee Creek 

 Beds of Colorado. Until both the typical Great Plains species 

 and the Virgin Valley forms are better known a final judgment 

 on the specific determination of the Nevada species may best be 

 postponed. 



A lower jaw, no. 10655, with the milk molars and a portion of 

 the first permanent molar in the process of eruption was referred 

 tentatively to H. equinus (Scott) by Gidley. 15 As this specimen 

 was represented principally by the lower milk dentition which 

 had not been known before, an exact comparison with the known 



Gidley, J. W., Notes on a Small Collection of Fossil Mammals from 

 Virgin Valley, Nevada, Univ. Calif. Publ. Bull. Dept. Geol., vol. 5, pp. 235- 

 246, 1908. 



is Op. (At., p. 236. 



