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



233 



by the late Miocene and early Pliocene. They all belong in an 

 epoch which follows the middle Miocene and precedes the middle 

 Pliocene. Farther collections from the Californian formations 

 will doubtless assist in determining their relationship to the 

 Thousand Creek Beds more definitely. 



SYSTEMATIC DESCRIPTIONS 



Pisces 



Scattered vertebrae and isolated skull bones of small fishes 

 were found at locality 1090 in the Virgin Valley Beds, and at 

 locality 1097 in the Thousand Creek Beds. The material was 

 very fragmentary and a satisfactory determination of the forms 

 represented seems improbable. 



Reptilia 



OPHIDIAN REMAINS 



Several snake vertebrae were found in an exposure of the 

 Thousand Creek Beds west of Railroad Ridge. They evidently 

 belong to several individuals, and it is not certain that they all 

 represent the same generic type. The vertebrae present are pre- 

 caudals with well-marked rib attachments (see figs la and lb). 

 The imperfect development of the neural 

 spines is presumably to be attributed to 

 their having been located near the posterior 

 portion of the rib-bearing division of the 



, , , n . , Figs, la and 16. 



vertebral series. The zygosphene is large Ophidian remains. Pre- 



and the zvgantral excavation deep. Hypa- cauc ^l vei ; teb J? e - No ; 



r . J r 19422, X 2. Thousand 



pophyseal prominences are present, but are Creek Beds, Thousand 



•• e , n n , -, Creek, Nevada. Fig-, 



imperfectly developed. la> po ' sterior view . fi | 



Occurrence: Thousand Creek Beds; lb, lateral view. 



locality 1103, Thousand Creek region, west of Railroad Ridge, 



Humboldt County, Nevada. 



CLEMMYS, sp. 



A number of fragments representing testudinate forms (fig. 

 2) from locality 1090 in the Virgin Valley Beds were referred 



