PELECYPODA—PRIONODESMA CEA . 



423 



Fig. 552. a, b, Pterin ea chemungensis, right and left valves; c, Limoptera can- 

 cellata ; d, surface of left valve of L. canceliata, enlarged; e, Pterinea consimilis, 

 left valve, a, b, c and e, X f. (Pal. N. Y., V.) 



XLVII. Actinodesma Sandburger. (Glyptodesma Hall.) 

 Like Pterinea but with wings elongate and narrow and less 

 strong limitation between body of shell and wing. Surface con- 

 centrically striated. Devonic. 



165. A. occidentale (Hall). (Fig. 553, c.) Devonic. 

 Differs from A. erectum in its more orbicular shell, more gibbous 



umbonal region, more rugose concentric striae, and less strong 

 limitation between the body of the shell and the much extended 

 posterior wing. 



Onondaga : Falls of the Ohio. 



166. A. erectum (Conrad). (Fig. 553, a, b.) Devonic. 

 Anterior wing limited by a distinct furrow. Surface covered 



with concentric striae which are more conspicuous upon the ears. 

 Hinge line often greatly extended. 



Hamilton : New York, Ohio, Indiana. 



