I 12 PALEONTOLOGY OF NEW YORK. 



The connected valves show ;i narrow ligamental area extending half the 

 length of tlic hinge. Other characters of the interior are unknown. 



One specimen has a length of 35 nun., height 21 mm., and hinge-line '2~> 

 mm. Another has a length of 25 mm., height 13 mm., and hinge-line 20 mm. 



This species resembles P. Eucrate. hut is less gibbous, more elongate, and 

 without angularity along the body. 



Formation and locality. In a conglomerate of the Chemung group at Panama. 

 ( lhautauqua county, N. V. 



Pttchoptebia galene, n. sp. 



PL WE 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 ; hast' 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, ver\ slightly concave just helow the 

 hinge-line; extremity angular. 



Surface of the body and wing marked by regular, line, interrupted or 

 undulating radii, which are oliscure or obsolete on the anterior portion : also 

 h\ ver\ line concentric lines, which art' crowded into irregular fascicles and 

 are lamellose on the anterior part of the valve. 



