424 PALEONTOLOGY OF NEW YORK. 



Two specimens measure respectively 35 and 40 mm. in length, and 35 and 

 38 mm. in height. 



In form this species somewhat resembles P. equilatera, but the beaks are more 

 al>ruptl\- attenuate, and the radii are much stronger and more prominent, with 

 comparatively wider interspaces. 



Formation and locality. In the shales of the Hamilton group, near Cumber- 

 land, Md. 



Panenka degener, n. sp. 



PLATE XCIV, FIG. 14. 



Shell of medium size, broadly obovate ; length and height nearly equal. Pal- 

 lial margin regularly curving, somewhat obliquely truncate on the posterior 

 side. 



Valves regularly convex, scarcely gibbous. 



Beaks prominent, elevated and strongly incurved. 



Surface marked by extremely fine, closely arranged concentric striae, and 

 by about forty-five nan-ow angular radii, which are less defined on the pos- 

 terior slope. Interspaces wider than the radii. 



The specimen described has a length of about 40 mm. 



This species is distinguished by its narrow, sharp, abruptly elevated radii. 

 Formation and locality. In the shales of the Hamilton group, at Pratt's falls, 

 Onondaga county, N. Y. 



Panenka robusta. 



PLATE LXX, FIGS. 22-24. 



Ill part Cardinptu robvjtta (Hall), S. A. Millkh. Cat. Am. Pal. F().s.s , p. 186. 1877. 



Cardiolaf robusta, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 70, figs. 22-24. 1883. 



Shell large, obliquely obovate ; length somewhat greater than the height. 

 Pallial margin vertical to the hinge-line in front, thence more regularly curv- 

 ing around the base to the posterior extremity. Post-inferior extremity 

 extended. 



