4. -JO PALEONTOLOGY OF NEW-YORK. 



PLATE CM. 



Fig. 1 a, b, c, d. Dorsal, ventral and profile views of this species. ( The figures, unfortunate- 

 ly, represent too many plioations by two on each side of the centre.) 



Fig. 1 t. The interior of the dorsal valve, showing the cardinal process, etc. 



Fig. ly. A cast or impression of a larger dorsal valve. 



The preceding, with a few specimens in similar condition, are all that I have been 

 able to obtain from the Oriskany sandstone in New- York. 



The following illustrations have been made from a study of the Maryland col- 

 lections at a later period : 



PLATE cm B. 



Fig. 1 a, h. Ventral and dorsal views of a specimen of this species. 



Fig. 1 c, d. Profile view of a specimen of the ordinary form of this species. 



Fig. 1 e. Interior of specimen with rounded extremities. 



Fig. 1/. Interior of tie dorsal valve of this species. 



Geological position and locality. In the Oriskany sandstone : Albany, Schoharie, 

 Greene and Ulster counties (New- York); Cumberland (Maryland), and in Virginia 

 and Canada. 



Leptocflplia finibriata ( n. s.). 



Plate cm B. Fig. 2 a-/. 



Shell small, longitudinally semielliptical, the length less than the width. 

 Ventral valve convex, more elevated along the middle, declining re- 

 gularly at the sides, the cardinal angles somewhat compressed : beak 

 small, little elevated above the cardinal line and slightly incurved, with 

 a minute rounded foramen at the extremity, the lower side of which, 

 when entire, is completed by two small deltidial pieces. Dorsal valve 

 flat or slightly convex, the front and lower lateral margins abruptly 

 inflected : beak straight ; hinge-line of the ventral valve more de- 

 clining, with border often grooved for the reception of the edge of the 

 dorsal valve. The hinge-line of closed valves often ornamented by 

 fibres or fimbria, forming a byssus-like appendage. 



Surface marked by about eleven or twelve rounded or subangular plica- 

 tions on each valve, two of which, in the middle of the ventral valve, 

 are more prominent and slightly larger than the others ; and between 



