246 PALEONTOLOGY OF THE EUREKA DISTRICT. 
Edmondia ? circularis, n. sp. ‘ 
Plate xxii, fig. 9. 
Shell large; general outline broadly ovate or subcircular, moderately 
convex, most prominent at the umbonal region. Hinge-line unknown, but 
probably arcuate; beaks depressed, curved over towards the cardinal line. 
Surface marked by concentric lines of growth as far as known. In- 
terior characters unknown. 
Dimensions : height, 5°"; width, 6°™; convexity of left valve, 1.5™. 
I know of no species with which to compare this. The generic refer- 
ence is made on the general form and appearance, as nothing is known of 
the interior characters. 
Formation and locality—Lower portion of Lower Carboniferous lime- 
stone in canon directly south of a small conical hill on east side of Secret- 
eaftion-road Canon, Eureka District, Nevada. 
Genus PLEUROPHORUS King. 
Pleurophorus Meeki, n. sp. 
Plate viii, fig. 3. 
Shell small, longitudinally oblong, widening posteriorly; moderately 
convex on the line of the umbonal slopes from the beak to the postero- 
basal margin, forming a nearly rounded section from the basal to the cardi- 
nal margin. Hinge-line long and nearly straight, with a narrow but well- 
defined lunette. Beaks located very near the anterior extremity. 
External surface of the shell unknown. The cast shows 5 or 6 ra- 
diating coste and traces of concentric lines of growth. 
The anterior adductor-muscular impression is bounded by a rather 
strong ridge on the posterior side; pallial line simple and extending to the 
slightly-marked posterior-adductor muscular scar; teeth unknown. 
This species is more nearly related to the English Permian species 
Pleurophorus costatus King (Mon. Perm. Foss., plate xv) than to any Ameri- 
‘an form that Lam acquainted with. The narrow form and posterior expan- 
sion serve to distinguish it from described species of the genus. 
Formation and locality.—Lower portion of Lower Carboniferous lime- 
stone in canon directly south of a small conical hill on east side of Secret- 
canon-road Canon, Eureka District, Nevada. 
