328 PALEONTOLOGY OF NEW YORK. 



NCCULITES NySSA. 

 PLATE XLVII, KlUS. 29, 30. 



NucitlUex ?fj/i>xa. Hall. Prelim. Notice Lainellil>ranchiat«, 2, y>. 5. 1870. 



In iMirt " " " Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 47, fig^s. 25-30. 1883. 



Shell of medium size, broadly ovate, wider anteriorly ; length about one-third 

 greater than the height ; basal margin regularly curving, abruptly rounding 

 into both extremities; posterior margin oblique, sulj-truncate above and 

 abruptly rounded below. Cardinal line short, slightly arcuate. Anterior end 

 short, rounded. 



Valves highly convex, gibbous in the umbonal region. 



Beaks at about the anterior fourth, incurved, rising a little above the hinge. 

 Umbonal ridge prominent, extending to the post-hiferior extremity. Cardinal 

 slope abrupt. 



Surface marked by fine concentric striae, which are slightly fasciculate, 

 producing low undulations of the surface. 



Muscular scars faintly impressed. Clavicular ridge narrow, curving toward 

 the anterior end and extending about two-thirds the height of the valve. 



The two specimens described measure respectively 18 and 14 mm. in 

 length and 12 and 10 mm. in height. 



This species closely resembles N. triqueter, but has a more ovate form ; the 

 other comparisons are given nnder the description of th.at species. 



Formation and localily. In concretionary layers in the shales of the Hamilton 

 group, on the shore of Lake Erie. 



