iGU PALEONTOLOGY OF NEW YORK. 



This species hears some general resenililaiuc in form to Actinopteria decussata 

 and A. Boi/di, hut is distinguished hy tlie ahsence of rays. It differs from 

 L. Greeni, fig. '.•, ph xx, in its more ohlique 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. 

 ri.ATE x.\, FIGS. 0, \i\ AND ri.ATF, i.xxxvui, Ki(;s. ■:i. *>. 



T^npterla Greeni,YiK\.\.. Pal. N. V., vol. v, i.t. 1. Plates a id Explanations : PI. 20, ti^'S. 9. l:i. .Ian.. 1883. 



Shell large, suh-rhomhoidal : Ixidy modei'ately ()hli(|ii('. hroadl^y ovate ; length 

 a little greater tlian the height; margins regularh rounded, somewhat 

 extended posteriorly. 



N'alves moderately and nearly ciinally convex; similar in character. 



Hinge-line straight, equalling or greater than the li'iigth of the shell. 



Beaks acute, anterior, inclined foi'ward, arching over the hinge in the 

 left valve ; less prominent in tli(> riglit. 



Ear short, limited hy a sulcus and sinus which is deeper in tlie right valve. 

 Wing large, triangular, defined only hy the abrupt bending of the striaj ; 

 margin concave ; extremity acute. 



Test thin, marked by numerous, closely arranged, concentric lines of 

 growth, and, at somewhat regular intervals, by sharp, projecting lamello.se 

 stria? ; and corresponding with these, are regular concentric undulations, 

 which are shown strongly on the cast, and but jiartially seen on the exterior 

 surface. The striae mark the wing in the same manner as the l)ody. and are 

 crowded on the ear. 



Ligamental area narrow, marked by a single groove. 



A large specimen measures ^u mm. in lengtli, •">] mm. in height, hinge- 

 line 58 mm. 



This species resembles L. Conradi, but is broader, with comparatively greater 

 heiglit, less obliquity, and le.'ss extended posterior wing. 



Formation and localities. In the shales of the Hamilton group at Bi'Uona. 

 Yates county, and on the shores of Cayuga and Cantmdaigua lakes, N. Y. 



