404 PALEONTOLOGY OF NEW YORK. 



tion near the anterior end. Posterior extremity apparently slightly gaping, 

 narrowly rounded ; the greatest extension being in the line of the longitud- 

 inal axis. Cardinal line straight, about two-thirds the length of the shell, 

 parallel with the basal margin. Anterior end short, gently declining from 

 the beaks and rounded below. 



Valves moderately convex. 



Beaks sub-anterior, low, closely appressed. Umbonal slope obscurely 

 marked by two low ridges, one extending to the post-inferior margin and the 

 other to the middle of the posterior end. Post-cardinal slope marked by an 

 obscure fold. Cincture narrow, not strongly defined, extending from the 

 beak to the basal margin at about the anterior third of the length of the 

 shell. 



Surface marked by fine concentric striae, which, from the appearance of the 

 cast, have been fasciculate on the anterior and posterior ends of the shell. 

 No radiating stria? have been observed. Interior unknown. 



The specimen described has a length of 49 mm. and a height of 18 mm. 



This species is entirely unlike the other forms here described in its elongate 

 hinge-line, gentle convexity of the valves and undefined umbonal ridge. 



Formation and locality. In the Waverly sandstones, at Newark, Licking 

 county, O. 



Sphenotus ^olcs. 



PLATE LXVI, YIQS. 31-K. 



Sanguinnlites jSitlus, Hall. Pi-elim. Notice Lamellibrancfaiata, 2, ]>. 46. 1K70. 



" " " Pal. N. Y., vol. V, i)t. 1. Plates and Explanations: PI. 66, figs. Sl-S."). 1883. 



Shell large, elongate-ovat«, sub-trapezoidal ; length more than twice the 

 height ; basal margin gently rounded, sometimes nearly straight. Posterior 

 extremity obliquely sub-truncate. Cardinal line straight, or slightly arch- 

 ing and gently declining posteriorly. Anterior end declining gently from 

 the beaks and abruptly rounded below. 



Valves convex below, gibbous in the middle and um1)onal region. 



Beaks sub-anterior, small, appressed, closely incurved, rising but little 



