48 



[Senate 



equal to the greatest width of the shell, terminating in minute 

 triangular extensions ; area sublinear, incurved beyond the 

 plane of the valves. Surface unknown. 



Internal casts of the ventral valve of this little shell are common in the 

 Oriskany ?andstoTie ; but no specimens have been met with, showing its 

 external charaetrers, nor have any specimens of the dorsal valve yet been 

 recognized. 



Geological position and locality. In the Oriskany sandstone, Albany 

 county. 



Strophomena woolworthana ( n. s.)> 



Pal. N.Y. Vol. iii, pi. 17, f. 1. 

 Shell semielliptical, often extremely elongate : ventral valve 

 concave towards the front and flat on the lateral margins, de- 

 pressed convex near the beak ; beak small, and scarcely rising 

 above the edge of the valve : dorsal valve convex, most elevated 

 near the front, and flattened near the um1)o ; beak not project- 

 ing : hinge-line straight, equal to the greatest width of the shell; 

 area linear, conspicuous, partly common to both valves ; foramen 

 broadly triangular, partly or entirely closed Surface finely 

 striated ; stride rounded, crowded, simple, increasing by im- 

 plantation ; concentrically crossed by closely arranged striae 

 and a few distant lines of growth. 



This species approaches in character to Strophoviena ( Leptccna ) sub- 

 plana ( Palaeontology of New-York. Vol. ii, pi. 53, f. S, 9 & 10 ) ; but 

 the shell is more robust, and the striaa more round and stronger than in 

 that shell. 



Geological position and locality. Shaly limestone of the Lower Hel- 

 derberg, Albany and Schoharie counties. 



STROrnOMKNA WOOLWORTHANA. 



