LAMELLIBRANCHIATA. 87 



Ckenipecten liratus. 



PLATE IX, FIG. 24; ami PLATE LXXXIII, FIG. 9. 

 Orenipectea liratus, Hall. Pal. N. V.. vol. v. ]it. 1. Plates and Explanations: PI. 9, fig. 24. .Ian., 1883. 



Shell small, obliquely sub-ovate; length a little less than the height; anterior 

 and basal margins rounded ; post-basal margin produced, and thence extend- 

 ing in a direct line to the beak. 



Left valve moderately convex, the greatest convexity distant one-third the 

 height of the valve from the beak. Right valve unknown. 



Hinge-line straight, short, length about one-third the height of the valve. 



Beak acute, erect, a little anterior to the centre of the shell, not rising 

 above the hinge. Umbonal region moderately elevated, subtending an acute 

 angle. 



Ears small, triangular, defined by moderate sulci ; the posterior ear the 

 larger. Byssal sinus not distinct. 



Surface marked by prominent, rounded, alternating radii, with interme- 

 diate smaller ones. There are about six larger rays, six smaller, and twice 

 that number of still smaller intermediate strise, all crossed by strong, regular, 

 concentric laminae of growth. The ears are apparently destitute of rays. 



The crenulations of the liganiental area are small and obscure. 



The specimen figured has a length of 20 mm., height 22 mm., hinge-line 

 7 mm. 



This species somewhat resembles C. micropterus in the radii, but differs in all 

 other characters. 



Formation and locality. Chemung group at East Randolph, Cattaraugus 

 county, N. Y. 



