245 



rays, with smaller intermediate ones on the left valve; con- 

 centric striae ; and a few obsolete i-ays on the right valve. 



Fonnd in the Stictopora and Demissa beds ( rather com- 

 mon); in the shale, down to twelve feet below the En- 

 crinal limestone, at Sections 6 and 7 (rare) ; in the shale 

 below the Nautilus bed, in Averv's Creek (rare) ; and at 

 "Hamburg and elsewhere on Lake Erie Shore." (Hall.) 



Genus ACTIN0PTERL4. Hall. 



[Ety. : Aktin, a ray ; 2'>f('>'f'>t. "wing.] 

 (1884 : Pal. N. Y., Vol. Y., Pt. I., p. xii.) 



"Characterized from Pterinea in the absence of a broad, 

 striated ligamental area, and strong cardinal and lateral 

 teeth. Right valve sulvconvex ; surface with fine ravs." 





?»**' 



Fig. 160. Actinopteria decussata. Left valve, showing the strongly decussated radii ; 

 right valve not preserving the radii (from Hall). 



