472 PALAEONTOLOGY OF NEW YORK. 



Cardinal line concave. Anterior end short, obliquely truncate above and 

 narrowly rounded below. 



Valves depressed-convex in the posterior and lower portions, becoming 

 gibbous in the middle and umbonal region. 



Beaks at about the anterior fourth, prominent, strongly incurved and ris- 

 ing above the hinge-line. Cincture indicated by a gentle, undetined depres- 

 sion, extending from the beaks downward, producing a slight sinuosity in 

 the basal margin. Umbonal slope angular above, becoming less prominent 

 below and extending to the post-inferior extremity. Post-cardinal slope 

 broad, marked by a more or less distinct longitudinal fold. 



Surface marked by fine concentric striae, which become fasciculate on the 

 anterior and posterior portions of the shell, and by radiating striae which 

 cover the body of the shell posterior to the beak, occupying the space from 

 the anterior side of the cincture to the umbonal ridge. 



Lunule marked by an abrupt infolding of the shell, leaving an angular 

 margin. 



Two specimens measure respectively 60 and 70 mm. in length, and 27 and 

 31 mm. in height. 



This species is distinguished by its large size and strong raflii which cover 

 the. body of the shell. In its general form and expression it is very similar to 

 some varieties of Cimitaria recurva. 



Formation and locality. In the sandstones of the Waverly group in Licking 

 county, Ohio. 



