368 PALEONTOLOGY OF NEW YORK. 



Beaks in advance of the anterior third, prominent and incurved. Umbonal 

 slope not defined. 



Surface marked by fine concentric striae and by angular, somewhat distant, 

 concentric folds, which become obsolete on the middle and posterior parts 

 of the shell. Interior unknown. 



Two valves of equal size have lengths of 14 mm. and heights of 10 mm. 



Formation and locality. In the shales of the Hamilton group, York, Living- 

 ston county, N. Y. 



Grammysia Eriopia. 



PLATE LXni, FIGS. 7, 8. 



Cardimniirpba Eriirpla, Hall. Pi-elim. Notice Lainellibraiichiata, 2, p. 92 1870. 



Pal. N. Y., vol. V, pt. 1. Plates ami Explanations : PI. 63, figs. 7, 8. 1883. 



Shell above the medium size, sub-circular or very broadly ovate ; length about 

 one-fifth greater than the height ; basal margin regularly rounded into the 

 broad posterior end. Cardinal line declining toward the posterior extremity. 

 Anterior end short, abruptly rounded below the lunule. 



Valves regularly convex below and posteriorly, gibbous in the middle 

 and above. 



Beaks at the anterior third or fourth, prominent and strongly incurved. 

 Umbonal ridge merging into the general convexity of the shell. Post- 

 cardinal slope marked by a low ridge which may become obsolete. 



Surface marked by fine concentric striae and by fine, distant, radiating 

 striae, principally developed on the posterior slope. Also marked by strong, 

 concentric folds which are principally shown on the umbo and the anterior 

 portion of the valve. In young shells the undulations are present on the 

 posterior slope, limited above by the post-cardinal ridge. Interior unknown. 



A small specimen has a length of 21.5 mm. and a height of 17 mm. A 

 larger individual has a length of 55 mm. 



This species bears some resemblance to G. obsoleta, but there is an absence 

 of any anterior radiating folds, the Vjeak is more erect and the concentric 



