FOSSILS OF THE CAEBONIFEEOUS. 



259 



The slope of the spire of L. bella is more like that of the minute Chem- 

 nitzia Icevigata Deshayes (Leth. Rossica, pi. xlii, figs. 6 a, &) of the Tertiary. 



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 PLEUEOTOMAEIA Defrance. 



Pleurotomaria nodomarginata McChesney. 

 Plate xviii, fig. 15. 



Pleurotomaria nodomarginata McChesney, 1860. Desc. New Species of Fossils, p. 70. 

 Trans. Chicago Acad. Sci., 1869, vol. i, p. 47, pi. vii, figs. 1 a-c. 



Notwithstanding- that Mr. McChesney gives the Hamilton Group as the 

 horizon from which P. nodomarginata was obtained, the identification is here 

 made with a shell coming from the Lower Carboniferous of the Eureka Dis- 

 trict. This conclusion is arrived at only after the most careful comparisons, 

 which appear to leave very little if any doubt of the specific identity of the 

 Nevada and Missouri shells. 



Formation and locality. Lower portion of the Carboniferous Group, east 

 side of Secret-canon-road Canon on east slope of a small conical hill, Eu- 

 reka District, Nevada. 



Pleurotomaria Nevadensis, n. sp. 

 Plate xxiv, figs. 2, 2 a. 



Shell turbinate; spire elevated, height and width subequal; volutions 

 five or six, expanding quite regularly to within a half of a volution of the 

 aperture, when it becomes more ventricose ; body volution angulated, 

 depressed convex above and rounded below; umbilicus small. Aperture 

 broadly oval to subcircular. 



Surface marked by strong, regular, revolving lines above and below 

 the peripheral band, crossed and cancellated by finer concentric striae that 

 cut into the revolving lines and give them a fine nodose appearance. The 

 concentric strise are directed a little backward from the suture to the band; 



