336 Thirty-fifth Keport on the State Museum. 



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, in its more oblique form and greater pro- 

 portional length. 



Formation and localities. In shales of the Hamilton group, on the 

 shore of Canandaigua lake, and at Bellona, Yates county, N. Y. 



LEIOPTERIA (xREESTI. 



o 



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, 

 equaling 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 concen- 

 tric 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. Liga- 

 mental 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. Oonradi, but is broader, with compara- 

 tively 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. 



Leiopteria Bafinesquii. 



Leiopteria Bafinesquii, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explana- 

 tions : PI. 15, fig. 11 ; pi. 20, figs. 6, 7. Jan., 1883. 



Shell of medium size, sub-rhomboidal ; body rather narrow above, 

 obliquely ovate ; height equaling or greater than the length ; 

 margins regularly curved ; the post-basal side extended ; anterior 



