306 
PALAEONTOLOGY OF NEW YORK. 
This species is much smaller than any form here described. It somewhat 
resembles G. truncata, but differs in its greater proportional height, the area 
between the carina and hinge-line is more convex; the concentric striae are 
much stronger and the indications of radiating striae are quite obscure. 
Formation and locality. At the base of the Chemung (Ithaca group) at Ithaca, 
N. Y. 
