174 
PALAEONTOLOGY OF NEW YORK. 
This species differs from L. Chemungensis in its more erect form, and the ear 
is without the strong fold and marked sulcus of that species; the wing is also 
less extended and the margin less concave. 
Formation and locality. In the Chemung group in the valley of Cayuta creek, 
Broome county, N. Y. 
Leiopteria Torreyi, n. sp. 
PLATE XXII, FIGS. 6, 7; and PLATE LXXXVIII, FIG. 11. 
Shell of medium size, rhomboidal, sub-falcate; body narrow-ovate, arcuate, 
oblique at an angle of less than 45° with the hinge; height equal to about 
two-thirds of the length; anterior and basal margins broadly curving from 
the byssal sinus; post-basal margin produced and abruptly recurved. 
Left valve very convex, gibbous in the middle and above. Right valve 
unknown. 
Hinge-line straight, about equal to the height of the valve. 
Beak sub-anterior, directed forward, acute, prominent and arching over 
the hinge. Umbonal region narrow, ventricose, well-defined, subtending an 
acute angle. 
Ear large, bending downward, marked by a strong oblique fold, limited by 
a broad, vertical byssal depression and shallow sinus; margin convex; 
extremity apparently obtuse. Wing joining the body above the posterior 
extremity, limited by the nearly vertical post-umbonal slope, which makes a 
more or less marked sulcus; margin concave ; extremity produced, acute. 
Surface marked by fine striae of growth which are somewliat regularly 
lamellose on the body of the valve. 
A left valve has a length of 29 mm., height 22 mm., hinge-line 21 mm. 
This species differs from L. Chemungensis in its proportionally greater length, 
narrower umbo, more convex and oblique left valve, and shorter wing. 
Formation and locality. In a sandstone and conglomerate of the Chemung 
group near Panama, N. Y. 
