82 



PAL^.ONTOLORY OF NEW-YORK. 



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

 mesial fold with a depression on each side. 



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



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



Fig. 7 c. Cardinal view, showing tlic 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 eounty. 



(Collrttion of Ci.l. Jkwktt. State Cvllictiun.) 



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