Lamellibranchiata. 259 



PTEEINOPECTEN, Hall. 

 Pterinopecten multiradiatus. 



Pterinopecten multiradiatus, Hall. Pal. N. Y. , vol. v, pt. 1 . Plates and 

 Explanations : PL 1, figs. 6, 7. Jan., 1883. 



Shell large, rhomboidal; body of the valve longitudinally obovate; 

 length and height nearly as five to four ; anterior and basal margins 

 regularly curved, the postero-basal margin produced and the body 

 of the shell extending thence in a direct line to the beak. Left valve 

 moderately and regularly convex. Right valve unknown. Hinge- 

 line straight, anterior, less than the length of the shell. Beak 

 obtuse, rounded, directed forward, slightly rising above the hinge. 

 Umbonal region ample, subtending an angle of about 105°. Ears 

 triangular, flat, moderately well-defined ; margins slightly concave ; 

 extremities rectangular. Posterior ear about twice the size of the 

 anterior, limited by a stronger ray and the abrupt post-cardinal 

 slope of the valve. The anterior ear is limited by a distinct but 

 undefined sulcus. Byssal sinus scarcely marked. 



Surface ornamented by numerous strong, distant, elevated, rounded 

 rays, with interspaces marked by a strong ray in the center, and 

 several finer ones on each side producing two series of alternations. 

 Concentric striae obscure. The arrangement of the rays gives the 

 surface a fasciculate aspect, especially marked in the impression of 

 the exterior. The rays on the posterior ear are sharp and simple, 

 while on the anterior ear they are similar to those on the body of 

 the shell. 



The specimen has a length of 48 mm., height 35 mm., hinge-line 

 about 36 mm. 



This species is distinguished from P. suborbicularis by its greater 

 length and doubly alternating radii. Though somewhat similar in 

 form to P. crenicostatus, the surface characters are very different. 



Formation and locality. In Corniferous limestone at Stafford, 

 Genesee county, N. Y. 



Pterinopecten" reflexus. 

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 Unpublished. 



Shell of medium size, rhomboidal, moderately oblique ; length one- 

 sixth greater than the height ; outline regularly curved to the 

 postero-basal margin, thence extending posteriorly. Left valve de- 



