128 
PALAEONTOLOGY OF NEW YORK. 
Actinopteria kappa, n. sp t 
PLATE LXXXIV, FIG. 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 striae, and are obsolete upon the ear. 
Interior unknown. 
The specimen has a length of 30 mm., height 20 mm., and hinge-line 
20 mm. 
This species 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. 
