76 PALEONTOLOGY OF THE EUKEKA DISTEICT. 



quite as great, but with more gradations between the valves with a scarcely 

 perceptible median fold and those where the fold is the prominent feature. 



The figure of the ventral valve, fig. 7, is of the type of that given by 

 the author of the species, and that of the dorsal valve, fig. 8, is not very 

 dissimilar, although representing what may prove to be a distinct species. 



Formation and localities. Lower portion of the Pogonip Group, and 

 upward about 1,000 feet on the east slope of ridge east of the Hamburg 

 mine; on the second ridge southeast of the Jackson mine, also northeast of 

 Adams Hill ; on the ridge southeast from the Wood Cone ; at the south- 

 west end of McCoy's Ridge, and on the west side of Goodwin Canon, Eureka 

 District, Nevada. 



LAMELLIBRANCHIATA. 



Geiius TELLINOMYA Hall. 



Tellinomya contracts Salter (?) 



Plate xi, tig. 15, 15 a. 



Ctenodonta contracta Salter, 1859. Canadian Organic Remains, Dec., i, p. 37, pi. viii, 

 figs. 4, 5. 



It is not improbable that the Nevada shell is specifically unlike T. 

 contracta, but with the specimens at hand it is difficult to determine the 

 differences if they exist. Mr. Billings has described a closely allied form 

 from the Quebec series of Newfoundland, but our species is more nearly 

 related to Salter's species from the Trenton limestone of Canada, to which, 

 for the present, it is referred. 



Formation and locality. Upper part of Pogonip Group, Fish Creek 

 Mountains, Eureka District, Nevada. It also occurs at the same horizon on 

 Pogonip Ridge, White Pine District, Nevada. 



Tellinomya ? Hamburgensis n. sp. 

 Plate xi, figs. 1, 1 a. 



Shell small, thin, convex; rounded subrhomboidal in outline with the 

 height and width subequal; beak elevated, incurved, and raised above the 

 hinge line anterior to the center of the shell. 



