422 NORTH AMERICAN INDEX FOSSILS. 



161. P. consimilis Hall. (Fig. 552, e.) Devonic. 



Differs from P. chemungensis in being shorter, proportionately 

 more extended on the hinge line, with wider ligamental area, more 

 distinct rays, and greatly different proportions of length and 

 breadth. 



Chemung Group : New York. 



XLVI. Limoptera Hall. 

 Differs from Pterinea in the less conspicuous separation of the 

 posterior wing from the body of the shell, and in the numerous 



Fig. 551. Pterinea (Cornellites) fiabellum. (Pal. N. Y., V. ) 



small pits for the attachment of umbonal muscles in the inter-pallial 

 area. Pallial line also formed of a series of small deep pits. 

 Devonic. 



162. L. cancellata Hall. (Fig. 552, c, d.) Devonic. 

 Body of shell nearly vertical to hinge line. Surface covered 



with regular sharp concentric striae and crossed by narrow rays 

 separated by broad flat interspaces. 

 Hamilton of Falls of the Ohio. 



163. L. macroptera (Conrad). (Fig. 553, d.) Devonic. 

 Right valve much less convex than left. Anterior ear very 



small. Surface marked with rays which become obscure below 

 the middle of the shell. Concentric striae lamellose. 

 Hamilton : New York, Ontario. 



164. L. obsoleta Hall. (Fig. 553, e.) Devonic. 

 Differs from L. macroptera in its less convexity, less angular 



posterior ear and in the rays being absent or very obscure. 

 Hamilton : New York. 



