188 Twenty-fourth Report on the State Museum, 



AviCULOPECTEN CRASSICOSTATA U. Sp. 



Shell below medium size, left valve depressed, convex; body of 

 shell oblique, hinge line straight, equal to three-fourths the length 

 of the shell ; anterior wing very small, separated from the body of 

 the shell by an abrupt, deep sinus ; posterior wing narrow, obtusely 

 pointed and extending nearly as far as the posterior extremity. 



Surface marked by strong, coarse, angular ribs, of which there are 

 about thirteen or fourteen on the body of the shell, with interme- 

 diate smaller ones ; about five obscure rays on the posterior wing ; 

 the radiating costse crossed by coarse, distant lamellose concentric 

 ridges. 



Formation and locality. In limestone of the age of the Upper 

 Helderberg group, at the Falls of the Ohio. Cabinet of Dr. 

 James Knapp. 



Cardiopsis ckassicosta n. sp. 



Shell large and robust, with moderately ventricose, broad, and 

 obliquely oval valves ; beaks strong, prominent, rounded, obtuse and 

 slightly incurved, situated considerably within the anterior extremity. 

 Anterior end rounded into the antero-basal margin ; margin more 

 abruptly curving around the postero-basal extremity, and thence 

 obliquely rounded forward and upward to the extremity of the short 

 hinge line, giving the greatest height and extension at the postero- 

 basal end. \ 



Surface marked by about forty-four or forty-five strong, simple, 

 rounded radii, which, with the exception of a few at the anterior end, 

 have a general backward direction. Those on the anterior end are 

 curved forward as they approach the margin of the shell, and are 

 generally broader than those of the middle of the valve. Height of 

 the valve, exclusive of the beaks, two and seven- tenths inches ; greatest 

 length, measured from the beaks to the postero-basal extremity, two 

 and four-tenths inches. 



This species approaches in character the O. rohusta of the Portage 

 group of New York, but differs slightly in the number of radii, that 

 one having an average number of thirty-eight ; it also difiers in the 

 closely arranged radii being without the intermediate space which 

 characterize that species. The beaks are also larger and more 

 prominent. 



Formation and locality. In the upper limestones at Louisville, 

 Ky. ; from the cabinet of Dr. James Knapp. Also in the Schoharie 

 grit in the State of Kew York. 



