82 



PALEONTOLOGY OP NBW-YORK. 



quite distinct ; in other cases they are less so, and sometimes there appears only a single 

 mesial fold with a depression on each side. 



Fig. 7 a. Ventral valve, with the large elevated beak of the dorsal valve incurved over it. 



Fig. 7 h. Dorsal view of the same specimen. 



Fig. 7 c. Cardinal view, showing the great convexity of the dorsal valve. 



Fig. 7 d. Profile view of the same. 



Position and locality. In the upper limestone of the group at Lockport, Niagara coimty. 



{Collection of Co\. J E-vfKTT. State Collection.) 



