PALAEONTOLOGY OF NEW YORK. 

 < Irentpecten micropterus. 



CI. \TK IX. WG 28 



pecten micropterux. Hall. Pal N. V.. vol. v. j>t. 1. Plates and Explanations: PI. !'. tigs. 2, 'A. 



Jan., iss:i. 



Shell small. Longitudinally and obliquely sub-elliptical; length somewhat 

 greater than the height; margins regularly rounded, produced behind and 



extending in nearly a direct line to the beak. 



Right valve depressed-convex. Left valve unknown. 



Hinge-line short, straight, anterior; length about one-third the height of 

 the valve. 



Beak low, obtuse. Umbonal region not strongly defined, subtending an 

 obtuse angle. 



Bars very small, nearly equal, bounded by shallow sulci. Byssal sinus 

 not distinct. 



Surface marked by numerous low, rounded radii, with wider interspaces 

 and smaller intermediate radii ; crossed by fine concentric lines of growth, 

 which arc stronger and crowded on the ears, forming their only surface 

 marking. 



Interior unknown. Ligamental area obscurely crenulate. 



The specimen described has a length of 18 mm., width 16 mm., hinge- 

 line 5 mm. 



This species resembles in form C. crenulatus, but differs in the radii, and in 

 the proportionally much shorter hinge-line. The surface markings are similar 

 to C. liratus, but it is different in its proportions of length and height. 



Formation and locality. In the shales of the Chemung group at Philipsburg, 

 Alleghany county, N. Y. 



