76 PALEONTOLOGY OF THE EUREKA DISTRICT. 
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. 
Genus TELLINOMYA Hall. 
Tellinomya contracta Salter (?) 
Plate xi, fig. 15, 15 a. 
Ctenodonta contracta Salter, 1859. Canadian Organic Remains, Dec., i, p. 37, pl. 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 0. sp. 
Plate xi, figs. 1, la. 
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. 
