243 



Found in the "f>hale and Encrinal limestone, aloiifj,- Lake 

 Erie Shore, Eighteen ^lile Creek, "Erie County, X. Y .' ( Hall. ) 



Genus PTERINOPECTEN. Hall. 



[Ety. : From Pterinea and Pecten.] 

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



'"Hinge line long: ears not well dehned. l)eing simple ex- 

 [)ansions or extensions of the upper lateral margins to the 

 hins-e line. Test ornamented with ravs." 



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

 X. Y., Vol. Y., Pt. I., p. 66. PI. XYH.) 



Distinguishing Clmracters. — Length and height nearly 

 equal; regularly rounded base: sharp constricted anterior 

 ear: gently concave pc:)sterior margin 

 of wing, with almost rectangular ex- ^^"^^Prf • f^T? 

 tremity; alternating radii of left ^ ,i^ 



valve, and sub-e(|ual radii of I'ight \ - / ^\-v<^'^' 

 valve. \ n,\\\\^' 



Found in the lower Moscow shale, '"^^ij**^^" 



at Section 4 (rare): in the shales of fig. i5o. pterinop>^cten con- 



spect^is. An exfoliated left valve 



the Demissa bed and down to seven- ^^'o™ Haii). 

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

 also in the upper Pleurodictyum bed, and the shale below 

 the X\iutilus bed, in Avery's Ravine. 



Pterinopecten hermes. Hall. (Fig. 1.57.) (Pal. X. Y., 

 Yol. Y., Pt. I., p. 64, PL XYIL) 



Distinguisliing Characters. — Longer than high: hinge line 

 extended, forming acute angle with posterior slope; regular 

 rounded surface stri^v, 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). 



