94 PALEONTOLOGY OF NEW-YORK. 



DISCING OF THE CHEMUNG GROUP. 



Discina iieglecta ( n. s.). 



PLATE I. 

 Shell elliptical. Dorsal valve convex : elevation of the apex above the 



plane of the margins about one-twelfth of an inch ; apex situated about 



one-third the length of the shell from the posterior margin. 

 Surface marked by crowded wrinkled concentric striae. 



A single specimen of the impression of the dorsal valve measures seven-tenths 

 of an inch in length, with a width of six-tenths of an inch. The dorsal valve of 

 another specimen of similar character is more nearly circular, the concentric 

 etrise are thin and elSxtated, and the interior shows a linear muscular impression. 



Other specimens are required for a full determination jof the characters of the 

 species. It is a more robust form, with the apex more elevated, than the D. lo- 

 densis; and the specimens maybe compared with D. seneca. 



Geological formation and locality. In the arenaceous shales of the Chemung 

 group, from the Inclined Plane at Ithaca, Tompkins county, N.Y. 



Discina eliiiira ( n. s.). 



PLATE II. 

 Dorsal valve very convex, transversely broad-oval ; breadth about seven- 

 tenths of an inch, and length half an inch : apex excentric, or about 

 one-third from the posterior margin. Ventral valve unknown. 

 Surface marked by extremely fine crowded striae. 



This specimen of the dorsal valve only, is noticed in anticipation of obtaining 

 materials for a full illustration. In the elevated dorsal valve, position of apex, 

 and fine striae, it bears some resemblance to the dorsal valve of D. grandis. 



Another specimen of similar character, but with the apex a little more de- 

 pressed, has a length of half an inch, with a transverse diameter of about one 

 inch. This specimen is essentially a cast in sandstone, and its surface markings 

 are not clearly preserved ; but it shows no important dilference from the pre- 

 ceding one, and for the present I unite the two under the same designation. 



Geological formation and locality. In the shales of the Chemung group : near 

 Elmira, N.Y., and in sandstone of the same group near Wellsborough, Pa. 



