484 PALEONTOLOGY OF NEW YORK. 



CYPRICARDINIA, Hall. 1859. 

 Cypricardinia planulata. 



ri,ATK LXXIX, FIGS. l-«. 



PUrinea planulata, Conrai>. Jiiiir. Aoa<L Nat. Sci., Phila., vol. viii, \>. 2.")1, jil. 13, fig-, l,"). 1842. 

 Cj/pricardinia " " Hall. Pi-eliin. Notice Lainellibraiichiata, 2, ji. 82. 1870. 



•• " " " Pal. N. Y., vol. V, pt. 1. Plates and Explanations: PI. 79, figs. 1-5. 



1883. 



Shell large, sub-rliomboid-ovate ; length one-third greater than the height ; 

 basal margin broadly curving, with a shallow sinus anterior to the middle. 

 Posterior extremity abruptly rounded below, sinuate and truncate above. 

 Cai'dinal line slightly arcuate, oblique. Anterior end short, declining rapidly 

 from the beak, regularly rounded below. 



Left valve depressed-convex below, more convex in the middle. Right 

 valve gibbous in the umbonal region. 



Beaks sub-anterior, appressed, rising but little above the hinge-line. Cinc- 

 ture very distinct, extending to the base of the shell. Umbonal slope 

 obtusely angular, prominent, extending to the post-inferior extremity. Post- 

 cardinal slope broad, sinuate ju.st above the umbonal ridge. 



Surface marked by fine concentric strife, and at regular intervals by 

 prominent concentric undulations. 



Muscular impressions and pallial line, as shown in figs. 3-5, of plate Ixxix, 

 representing casts of the interior. 



Four specimens measure respectively 15, 21, 26 and 27 mm. in length, and 

 10, 14, 17 and 19 mm. in height. A large specimen has a length of 30 mm. 



This shell is distinguished by its large size, broad form and distinct sinuosity 

 extending along the post-cardinal slope, just above the umbonal ridge. 



Formation and localities. In the Schoharie grit, in the Helderberg mountains, 

 and in Schohfirie county, N. Y. 



