242 PALEONTOLOGY OF THE EUREKA DISTRICT. 
Dimensions: height, 6™"; *width, 7"; convexity or depth of right 
valve, 2™™. 
This small species is more closely allied in external form to Nucula ? 
levata Hall (Pal. N. Y., vol. i, p. 150, pl. xxxiv, figs. 1 a-i, 1847), of the 
Trenton limestone of New York than to any Carboniferous species that 
I am acquainted with. 
Formation and locality—Lower portion of Lower Carboniferous lime- 
stone in canon directly south of conical hill on east side of Secret-cation- 
road Canon, Eureka District, Nevada. 
Genus SOLENOMYA Lamarck. 
Solenomya curta, n. sp. 
Plate xxii, figs. 6, 11. 
Outline transversely elliptical or oblong-oval, moderately convex. 
Hinge-line about one-half the length of the shell; beak depressed, situated 
at the anterior third of the shell. 
Surface with narrow undulations of growth, crossed by nearly obso- 
lete, radiating, flat plications, with finer striz between. 
Interior characters unknown. 
Dimensions: height, 2.25™; width, 3.75™; convexity or depth of left 
valve, 5°. A smaller, more elongate right valve has a height of 1.5°™, and 
a width of 3°. With but one specimen of the latter to study it is referred 
to this species somewhat provisionally, as there is no series of forms unit- 
ing it with the former. 
I know of no species with which this can be directly compared, its 
shorter, higher form distinguishing it from described species. 
Formation and locality—Lower portion of Lower Carboniferous lime- 
stone on east slope of a small conical hill on the east side of Secret-cantion- 
road Canon, Eureka District, Nevada. 
