New Species of Fossils. 213 



The specific name is given in honor of the late Mr. E. Billings, 

 Palaeontologist of the Geological Survey of Canada. 



Formation and locality. Birdseye limestone, Buck's Quarry, 

 Russia, Herkimer Co., N". Y. 



Genus BEYRICHIA— Jfc6%. 



BeYKICHIA BELLA, n. Sp. 



Plate IT, figs. 11, \\a. 



Carapace large as compared with associated species. Length, 3.75 

 mm., width, 2 mm. at the broadest part near the center. The 

 hinge line is straight and shorter than the length of the valves, each 

 end projecting. The center of the valve is strongly convex, and 

 separated from the margin by a narrow channel ; a strong deep sul- 

 cus crosses the valve obliquely from the dorsal to the ventral margin, 

 separating a large convex lobe on the anterior half : a second sulcus, 

 not as deep as the anterior, crosses from the posterior third of the 

 dorsal margin, and unites with the anterior sulcus two-thirds of the 

 distance between the dorsal and ventral margins, separating a sub tri- 

 angular lobe adjoining the dorsal border and a narrower elongate 

 strongly convex lobe on the posterior portion ; this lobe is crossed by 

 a. transverse furrow near the dorsal end, which separates a small de- 

 pressed lobe within the postero-dorsal angle. 



Surface finely granulose under a strong magnifying power. 



Beyrichia decora and B. venusta Billings of the silurian of anti- 

 costi belong to the same group as B. oella. 



Formation and locality. Upper portion of the Trenton limestone, 

 Trenton Falls, N, Y. 



Genus LEPERDITIA, Roualt. 



Subgenus Isochilina Jones. 



Lepeeditia (Isochilina) aemata, n. sp. 



Plate 17, fig. 10. 



Carapace elongate, moderately convex ; length, 8.5 mm., width, 

 5 mm. Hinge line straight to the lateral angles of the valve where 

 it curves up and unites with the projecting lateral margins to form 

 the produced anterior and postero-dorsal angles ; anterior extremity 

 broadly rounded ; ventral curve uniform : posterior extremity ob- 

 liquely rounded to the ventral curve. From the point of greatest 

 convexity on the lower central half of the valve a strong unciform- 

 shaped spine projects obliquely outward, the apex extending beyond 

 the ventral margin and curving toward the anterior extremity of the 

 valve ; the section of the spine at the base is elliptical, becoming 

 sharply angular on the posterior side as it nears the apex. 



