372 PALAEONTOLOGY OF NEW YORK. 



Grammtsia globosa. 



PLATE LXII, FIGS. 10-19. 



Chvmmyiiia gMntsa, Hall. Prelim. Notice Lamellibranchiata, 2, p. 57. 1870. 



Cardimnorpha cordatux, H.\i.l. Piil. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 62, figs. 10-19. 1883. 



Shkll below the medium size, sub-globose ; valves sub-circular, or very broadly 

 ovate; length a little greater than the height; basal margin- regularly 

 rounded, curving into the broad, rounded posterior margin. Cardinal line 

 about half the length of the shell. Escutcheon strongly marked, limited on 

 the exterior by a strong fold, with a smaller intermediate fold. Anterior end 

 somewhat broadly rounded below the lunule, which is distinctly marked and 

 sometimes margined by a narrow fold. 



Valves ventricose. 



Beaks at about the anterior third, very prominent and incurved. Umbonal 

 slope rounded, not defined from the general convexity of the shell, sometimes 

 with a narrow obsolescent fold. 



Surface marked by fine concentric striae and strong rounded or sub-angular 

 concentric folds, which are sometimes duplicate, all becoming obsolete on the 

 posterior slope. Interior unknown. 



Two specimens measure respectively 20 and 28 mm. in length, 20 and 23 

 mm. in height, and 20 and 20 mm. in the depth of both valves. A larger 

 specimen has a length of 33 mm. and a height of 27 mm. 



This species bears some resemblance to the shorter forms of G. arcuata, but 

 differs in its ventricose character and circular form. Among all the collections 

 which have been made no individuals have been noticed which are larger than 

 those illustrated on plate Ixii.* 



Formation and localities. In the shales of the Hamilton group, in Schoharie 

 county ; Leonardsville and Hamilton, Madison county, Pratt's falls, Onon- 

 daga county, and on the shores of Cayuga and Canandaigua lakes, N. Y. 



* The reference to the genus Cabdiomorpha, aa above cited, arose from copying an erroneous recoi-d of 

 the species. At that time, the name Orammysia globosa, previously g^ven, was overlooked. 



