Lamellibranchiata. 267 



Pterinopecte:n" filitextus* 



Pterinopecten filitextus, Hall. Pal. N. Y., vol, v. pt. 1. Plates and Explana- 

 tions : PI. 17, fig. 22. Jan., 1883. 



Shell larger than medium size, transversely semi-elliptical, scarcely 

 oblique ; length somewhat greater than the height ; margins regu- 

 larly rounded, less convex on the posterior side. Left valve mod- 

 erately convex. Right valve flat or concave. Hinge-line straight, 

 about as long as the length of the shell, not extended anteriorly 

 beyond the margin. Beaks obtuse, anterior to the middle of the 

 valve, directed forward, not well-defined. Umbonal region not 

 strongly marked. Ears unequal. Posterior ear wide-triangular, 

 extending as far as the margin of the shell, its limits undefined ; 

 margin nearly straight ; extremity nearly rectangular. Anterior 

 ear small, limited by a strong sulcus ; margin concave ; extremity 

 obtuse. Byssal sinus in the left valve moderate ; in the right valve 

 well-marked. 



Test of right valve thin, marked by fine filiform radii, with much 

 wider interspaces which are marked by finer rays ; the same char- 

 acter continuing on the posterior ear, with more equal rays. The 

 entire surface is marked by fine, close, concentric lines of growth, 

 with lamellose elevations at unequal intervals. Hinge-ligament 

 marked by several parallel grooves. 



A right valve measures approximately 35 mm. in length, and 29 

 mm. in height. 



In general form this species resembles P. conspectus, but is pro- 

 portionally longer, and the surface markings are different. 



Formation and localities. In the Hamilton group near Cardiff, 

 Onondaga county, and from a bowlder of Hamilton shale at Pine Val- 

 ley, Chemung county, N. Y. 



Pterinopecten intermedius. 



Pterinopecten conspectus, in part, Hall. Pal. N. Y., vol. v, pt. 1. Plates and 



Explanations : PI. 17, fig. 19. Jan., 1883. 

 Pterinopecten intermedins, Hall. Pal. N. Y., vol. v, pt. 1. Unpublished. 



Shell of medium size, sub-rhomboidal, oblique ; length one-fourth 

 greater than the height ; margins regularly rounded, more convex 

 on the post-basal side. Left valve convex, greatest convexity below 

 the umbo. Right valve unknown. Hinge-line straight, somewhat 

 anterior ; length greater than the length of the valve. Beak acute, 

 well-defined, arching over the hinge, directed forward, situated an- 



