252 PALEONTOLOGY OF THE EUKEKA DISTEICT. 



Genus SCHIZODUS King. 

 Schizodus cuneatus Meek. 



Plate xx, fig. 8. 

 Schizodus cuneattis Meek, 1875. Pal. Ohio, vol. ii, p. 336, pi. xx, fig. 7. 



There does not appear to be any points of specific difference between 

 the Ohio shell illustrated by Mr. Meek and the examples of this species 

 from Nevada. The latter are proportionally a little narrower, but this may 

 be owing to the state of preservation, as the Ohio shell is compressed in a 

 shale, and the Nevada specimens retain their natural convexity and outline. 



Formation and locality. Lower portion of the Carboniferous group, on 

 the eastern slope of a small conical hill on the east side of Secret canon- 

 road Canon, Eureka District, Nevada. 



Schizodus deparcus n. sp. 

 Plate xxii, fig. 5. 



Shell large, transversely suborbicular, moderately convex; urnbonal 

 ridge rounded and passing into the postero-dorsal slope without any per- 

 ceptible angle being developed. Beak small, elevated, incurved, and sit- 

 uated a little anterior to the center of the shell. 



Surface smooth as far as known, except a few radiating lines on the 

 postero-dorsal slope. 



Anterior muscular scar not large, ovate in outline ; posterior scar elon- 

 gate, and crossed longitudinally by two slightly depressed lines, probably 

 from the radiating lines of the postero-dorsal slope of the shell. Pallial line 

 simple. 



Dimensions: height, 4.25 m ; width, f, cm ; convexity or depth of right 

 valve, 1.5 cm . In size this species approaches Scliizodus cuneatus (ante). It 

 differs in being less erect, less angular in outline, and in having a smooth 

 surface. 



Formation and locality. Lower portion of Lower Carboniferous lime- 

 stone on east slope of a small conical hill on the east side of Secret-canon- 

 road Canon, Eureka District, Nevada. 



