ORISKANY SANDSTONE. 419 



Leptiena? nucleata. 



Plate XCIV. Fia. 1 a, b, c, d. 

 LepUtna nudtata : Hall, Regents' Report of 1856, p. 47; PalaBozoio Fossils, 1857, p. 7. 



Shell semicircular. Ventral valve extremely gibbous, abruptly depressed 

 or flattened towards the lateral extremities : beak (internal cast) very 

 abruptly incurved, and divided by a central groove which extends 

 downwards nearly to the middle of the valve. Dorsal valve unknown : 

 hinge-line equal to the greatest width of the shell, terminating in 

 minute triangular extensions ; area sublinear, incurved beyond the 

 plane of the valves. Surface unknown. 



Internal casts of the ventral valve of this little shell are common in the Oriskany 

 sandstone; but I have seen no specimens showing the external characters, nor have 

 any specimens of the dorsal valve yet been recognized. I have referred it provisio- 

 nally to the Genus Lept-ena, but with much doubt as to its true generic relations; 



Fig. 1 a, b. Ventral and profile views of the cast. 



Fig. 1 c. Cardinal view. 



Fig. 1 d. Profile view enlarged. 



Geological position and locality. In the Oriskany sandstone : Albany county. 



Kpirifer snbmucronatiis. 



Plate XCVI. Fio. 7 a-/. 

 Spirifer tubmucroncdus : Hall, R^ents' Report of 1856, p. 62; Palaeozoic Fossils, 1857, p. 22. 



Shell semicircular, with the extremities mucronate : valves equally and 

 moderately convex. Ventral valve regularly convex, a little flattened 

 at the lateral extremities : beak little elevated above the area line, 

 and slightly incurved ; mesial sinus shallow, and flat in the middle ; 

 area of moderate height ; foramen somewhat large, often partially 

 closed. Dorsal valve depresso-convex in the middle and flattened 

 laterally, often a little concave towards the extremities : mesial fold 

 distinctly defined, equal in width to the two adjoining costas, somewhat 



