FOSSILS OF THE CARBONIFEROUS. 



255 



Surface covered with fine, undulating strise of growth that are crowded 

 together irregularly, forming slight concentric undulations. 



The arcuate form of the body-whorl distinguishes this species from 

 Pldtyceras acutirostris Hall (Geol. Surv. Iowa, vol. i, pt. 2, p. 665, pi. xxiii, 

 fig. 1-1) of the Lower Carboniferous of Indiana, etc., the most nearly allied 

 species. 



Formation and locality. Lower portion of Lower Carboniferous lime- 

 stone, in canon directly north of a small conical hill on east side of Secret- 

 canon-road Canon, Eureka District, Nevada. 



Genus PLATYOSTOMA Conrad. 



Platyostoma iuornatum n. sp. 



Plate xxiv, figs. 3, 3 a. 



Shell subglobose; spire elevated above the body whorl ; volutions three 

 or four, and perhaps a fifth very minute one, that is not preserved in the 

 specimen illustrated. The outer volution expanding towards the aperture, 

 but scarcely ventricose; aperture vertically ovate or subrhomboidal; the 

 columellar lip appears to have been reflexed. 



The few fragments of the outer shell that are preserved show it to 

 have been nearly if not quite smooth. 



This species resembles some forms of Platyostoma lineatum (ante, p. 185) 

 of the Devonian of New York. 



Formation and locality. Lower portion of Lower Carboniferous lime- 

 stone, in canon directly south of a small conical hill on the east side of Secret- 

 canon-road Canon, Eureka District, Nevada. 



Genus EUOMPHALDS Sowerby. 



Euomphalus (Straparollus) subrugosus M. & W. 

 Plate xviii, fig. 19. 



Euomphalus rugosus Hall, 1858. Geol. Surv. Iowa, vol. i, pt. 2, p. 722, pi. xxix, figs. 



14a-c. (Not Euomphalus rugosus Sowerby, 1849.) 

 Serpula \ Spirorbis) planorbitcs Geinitz, 1866. Carb. uud Dyas in Nebraska, p. 2, pi. 



i, fig. 6, (not of Munster). 



