«68 PAL-EONTOLOGY OF NEW-YORK. 



Cypricardinia conceiitiica ( n. b.)- 



Plate L. Fiq. 2. 



Shell oval-ovate, broader behind, compressed, narrowed and regularly, 

 rounded at the anterior end : umbones extremely depressed ; hiuge- 

 line scarcely curved ; base regularly curving ; posterior extremity 

 somewhat abruptly rounded : a defined oblique ridge from the beak 

 backwards. 



Surface marked by strong concentric ridges, which are more distinct on 



the anterior and central portions of the shell, and become obsolete 



above the oblique ridge. 



Fig. 2. The right valve of this species. The figure represents the shell as more acute an- 

 teriorly, and more oblique on the posterior margin than it is in reality, while the 

 conccbtric ridges are represented as bending too acutely upon the posterior ridge. 



Geological position and locality. In the compact calcareous layers of the central 

 portions of the Lower Helderberg group : Schoharie county. 



Cypricardinia crassa ( n. s.). 



Plate L. Fio. 3. 



Shell ' thick, subrhomboidal : umbones depressed ; anterior side short, 



rounded ; posterior side much wider, somewhat obliquely truncated ; 



hinge-line short, the oblique ridge extending to the postero-lateral 



margin. 

 Surface marked by a few broad, distinct, thickened lamelljB, and finer 



striae of growth. 



Fig. 3. The right valve, natural size. The posterior side is somewhat broken and obscure. 



Geological position and locality. In the shaly limestone of the Lower Helderberg 

 group : Schoharie. 



