FOSSILS OF THE CARBONIFEROUS. 



249 



nearly transverse along the center, curving up rather abruptly anteriorly, 

 and more gently at the posterior end; posterior line abruptly rounded at 

 the point of greatest extension on a line with the center of the shell, above 

 which it curves forward to the straight cardinal line. Valves marked by 

 several distinct, but not prominent, ridges on the postero-cardinal slope. 



Surface ornamented by fine concentric striae, and a few obscure lines 

 of growth. 



Formation and locality. Lower horizon of the Carboniferous Group, 

 eastern slope of a small conical hill on east side of Secret-cafion-road 

 Can" on, Eureka District, Nevada. 



Sanguinolites f Naenia, n. sp. 

 Plate xix, fig. 9. 



Shell small, transversely elongate, the height being one-half the length; 

 beaks small, depressed, and situated on the anterior third; anterior end nar- 

 row, somewhat elongate and so abruptly rounded as to be almost angular; 

 basal line slightly sinuate midway and curving up at each end; posterior 

 end broadly rounded; cardinal line nearly straight The general surface 

 of the valves is moderately convex, with a slight umbonal ridge extending 

 from the beak to the postero-basal curve, and also a rather broad, shallow 

 mesial depression. 



Surface marked by several well-defined, concentric undulations of 

 growth. 



Formation and locality. Lower horizon of the Carboniferous Group, 

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

 Canon, Eureka District, Nevada. 



Sanguinolites striatus, n. sp. 

 Plate xxiii, fig. 7. 



Shell transversely elongate-oval, compressed convex, posterior umbonal 

 slope angular. Cardinal line long, straight. Beak appressed, situated at 

 about the anterior third. 



