246 PALEONTOLOGY OF THE EUBEKA DISTRICT. 



Edmondia f 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 cm ; width, 6 cm ; convexity of left valve, 1.5 cm . 



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- 

 canon-road Canon, Eureka District, Nevada. 



Genus PLEUROPHORUS King. 



Pleuiophorus Meeki, u. 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 costse 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- 

 can form that I am 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. 



