L28 1'AL^ONTOLOGY OF NEW YORK. 



A i TINOPTEHIA KAPPA, 1). sp. ' 

 PLATE IAWIV, H1G. 13. 



Shell of medium size, rhomboidal; body narrowly ovate, oblique at an angle of 

 less than 45 ; length one-third greater than the height : anterior margin 

 oblique, rounded into the broadly curved basal margin; posterior end abruptly 



rounded. 



Left valve depressed below, convex from the middle upward. Right valve 

 unknown. 



Hinge-line straight, equal to the height of the valve. 



Beak sub-anterior, prominent, arching over the hinge-line. Umbonal 

 region moderately gibbous. 



Ear short, oblique, rounded anteriorly, defined by a distinct byssal depres- 

 sion. Wing triangular, joining the body nearly two-thirds of the length from 

 the beak; margin oblique, concave; extremity produced, acute. 



Test thin, marked by fine, concentric, irregularly fasciculating striae, giving 

 an undulated appearance to the surface, and by filiform, interrupted and 

 undulating radii, with wider interspaces, which sometimes show fine 

 intercalated rays. The radii upon the wing are prominent and cancellated 

 by the concentric strife, and are obsolete upon the ear. 



Interior unknown. 



The specimen has a length of 30 nun., height '20 mm., and hinge-line 

 20 mm. 



This specie- differs from A. epsilon, in the greater obliquity, longer hinge-line, 

 and more distant radii. 



Formation and locality. In the lower member of the Chemung group at 

 Ithaca, N. Y. 



