160 
PALEONTOLOGY OF NEW YORK. 
This species bears some general resemblance in form to Actinopteria decussata. 
and A. Boydi, but is distinguished by the absence of rays. It differs from 
L. Greeni, fig. 9, pi. xx, in its more oblique form and greater proportional length. 
Formation and localities. In shales of the Hamilton group, on the shore of 
Canandaigua lake, and at Bellona, Yates county, N. Y. 
Leiopteria Greeni. 
PLATE XX, FIGS. 9, 12; and PLATE LXXXVIII, FIGS. 21, 22. 
Leiopteria Greeni, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 20, figs. 9,12. Jan., 1883. 
Shell large, sub-rhomboidal; body moderately oblique, broadly ovate; length 
a little greater than the height; margins regularly rounded, somewhat 
extended posteriorly. 
Valves moderately and nearly equally convex; similar in character. 
Hinge-line straight, equalling or greater than the length of the shell. 
Beaks acute, anterior, inclined forward, arching over the hinge in the 
left valve ; less prominent in the right. 
Ear short, limited by a sulcus and sinus which is deeper in the right valve. 
Wing large, triangular, defined only by the abrupt bending of the striae; 
margin concave; extremity acute. 
Test thin, marked by numerous, closely arranged, concentric lines of 
growth, and, at somewhat regular intervals, by sharp, projecting lamellose 
striae; and corresponding with these, are regular concentric undulations, 
which are shown strongly on the cast, and but partially seen on the exterior 
surface. The striae mark the wing in the same manner as the body, and are 
crowded on the ear. 
Ligamental area narrow, marked by a single groove. 
A large specimen measures 57 mm. in length, 51 mm. in height, hinge¬ 
line 58 mm. 
This species resembles L. Conradi, but is broader, with comparatively greater 
height, less obliquity, and less extended posterior wing. 
Formation and localities. In the shales of the Hamilton group at Bellona, 
Yates county, and on the shores of Cayuga and Canandaigua lakes, N. Y. 
