142 
PALAEONTOLOGY OF NEW YORK. 
The connected valves show a narrow ligamental area extending half the 
length of the hinge. Other characters of the interior are unknown. 
One specimen has a length of 35 mm., height 21 mm., and hinge-line 25 
mm. Another has a length of 25 mm., height 13 mm., and hinge-line 20 mm. 
This species resembles P. Eucrate , but is less 'gibbous, more elongate, and 
without angularity along the body. 
Formation and locality. In a conglomerate of the Chemung group at Panama, 
Chautauqua county, N. Y. 
Ptychopteria galene, n. sp. 
PLATE LXXXV, FIGS. 29-31. 
Shell small, rhomboidal; body sub-elliptical, oblique at an angle of about 40° 
with the hinge; height greater than half the length ; ante-byssal margin 
oblique, curving gently into a shallow sinus; base regularly rounded; 
posterior end abruptly recurved. 
Left valve convex, moderately gibbous on the umbo, and sub-angular along 
the upper half. Right valve less convex above, depressed-convex in the 
lower part. 
Hinge-line straight, length greater than the height of the valve. 
Beaks near the anterior third of the hinge, inclined forward, prominent, 
arching over the hinge-line. Umbo gibbous, subtending somewhat less than 
a right angle. 
Anterior end small, limited by the shallow, nearly vertical byssal depres¬ 
sion ; extremity acute. Wing wide-triangular, joining the body near 
the posterior end; limiting furrow distinct; fold wide and moderately 
prominent; margin obliquely truncate, very slightly concave just below the 
hinge-line; extremity angular. 
Surface of the body and wing marked by regular, fine, interrupted or 
undulating radii, which are obscure or obsolete on the anterior portion; also 
by very fine concentric lines, which are crowded into irregular fascicles and 
are lamellose on the anterior part of the valve. 
