243 



Found in the "shale and Enerinal limestone, along Lake 

 Erie Shore, Eighteen Mile Creek, Erie County. X. V." ( Hall. ) 



Genus PTEMNOPECTEX. Hall. 



[Ety. : From Pterinea and Pecten.] 

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



"Hinge line long; ears not well denned, being simple ex- 

 pansions or extensions of the upper lateral margins to the 

 hinge line. Test ornamented with rays." 



Pterinopecten conspectus. Hall. (Fig. 156.) (Pal. 

 N. Y., Vol. V., Pt. I., p. 66, PI. XVII.) 



Distinguishing Characters. — Length and height nearly 

 equal ; regularly rounded base ; sharp constricted anterior 

 ear; gently concave posterior margin 

 of wing, with almost rectangular ex- 

 tremity; alternating radii of left 

 valve, and sub-equal radii of right 

 valve. 



Found in the lower Moscow shale, 



at Section 4 (rare) ; in the shales of fig. ise. pterinopecten con- 

 spectus. An exfoliated left valve 



the Demissa bed and down to seven- inomHaiii. 

 teen feet below the Enerinal limestone, at Sections 6 and 7 ; 

 also in the upper Pleurodictyum bed, and the shale below 

 the Nautilus bed, in Averv's Ravine. 



Pterinopecten hermes. Hall. (Fig. 157. ) (Pal. X. Y., 

 Vol. V., Pt. I., p. 64, PI. XVII.) 



Distinguishing Characters. — Longer than high; hinge line 

 extended, forming acute angle with posterior slope; regular 

 rounded surface stria?, with wider interspaces. 



*^.,..^ 



Fig. 157. Pterinopecten hermes. Two exterior views and one interior view of left 

 valves — the ear of the first specimen is represented too acute (from Hall). 



