398 Thirty-fifth Eeport on the State Museum. 



The left valve described has a length along the hinge-line of 80 

 mm., height 40 mm.; measured along the axis of the body the length 

 is about 70 mm., and the anterior truncation is 25 mm. long. 



The specimen described is a cast of the interior, preserving the 

 surface markings in a subdued condition. The anterior margin 

 appears to have been slightly incurved and the truncation resembles 

 that in some forms of Solen". 



Formation and locality. In the Oriskany sandstone, Schoharie, 

 N. Y. 



Pal^opin-^a recurva. 



Palceopinna recurva, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explana- 

 tions : PI. 25, fig. 19. Jan., 1883. 



Shell large, elongate semi-elliptical ; axis making an angle with the 

 hinge-line of from 20° to 25°; length greater than twice the height; 

 basal margin very broadly curving; posterior margin rapidly 

 rounding and recurving toward the beak. Left valve depressed- 

 convex below, convex above and becoming gibbous toward the beak. 

 Eight valve unknown. Hinge-line straight, not extending as far as 

 the posterior extremity. Anterior end unknown. Wing not defined ; 

 margin continuous with the post-basal margin and abruptly incurving 

 at the extremity. 



Test thin, marked by fine sub-equal striae of growth, which 

 become lamellose on the pallial margin ; and by radii of unequal 

 strength, which are sometimes strongly crenulated by the concentric 

 striae. Anterior to the middle of the shell the radii are obscure. 



The specimen described is imperfect on the anterior end but pre- 

 serves a length of 120 mm., and a height of 62 mm. 



This species differs from the preceding in its larger size, broadly 

 rounded posterior extremity, and the hinge not extending as far as the 

 posterior margin ; the body is also more oblique and less convex. 



Formation and locality. In limestone of the Upper Helderberg 

 group, Stafford, Genesee county, N Y. 



