OS I'ALjEONTOLOGY of NEU YORK. 



Beaks obtuse, anterior to tlic miilillc of the valve, directcil foiwiird, not 

 well defined. Fndjonal region not strongly marked. 



Ears une(inal. Posterior ear wide-triangular, extending as far as the mar- 

 gin of the shell, its limits undefined ; margin nearly straight ; extremity- ree- 

 tangular. Anterior ear small, limited by a strong sulcus ; margin concave; 

 extremity obtuse. Byssal sinus in the left valve moderate; in the right 

 valve well-marked. 



Test of right viilve tliin, marked by fine filiform radii, with nnuli \\ ider 

 interspcaces which are marked hy finer rays; the same character continuing 

 on the posterior ear, with more e(inal rays. The entire surface is iiiinkcil 

 by fine, close, concentric lines of growth, with lanicllose elevations at unci|iial 

 intervals. 



Hinge-ligament marked by several parallel grooves. 



A right valve measures approximately 35 mm. in length, and li'.i mm. in 

 height. 



In general form this species resembles P. conspectus, T)nt is j)roportionally 

 longer, and the surface markings are different. 



Formation and localities. In the Hamilton group near Cai-diff, Onondaga 

 county, and from a bowlder of Hamilton shale at Pine Valley, Chennmg 

 county, N. Y. 



Pterinopecten intermedius, n. sp. 



I'l.ATK XVII. FKi 19; akI) I'LATK I.XXXIII, Fl(;s. 4, 6. 



I'terhiopeclcii cifiispKutits, in pari. Ham,. I'al. N. V., vol. v. jit. 1. I'latos aiKl Kxiiliinjitidiis : PI. 17. ti^r. lil, 



.Ian., 1883. 



Shell of medium size, sul)-rliomlioi(lal, obli([ue ; ienglii one-fourth greater than 

 the height; margins regularl\ i-ouiided, nu)re convex on the post-l)asal side. 



Left valve convex, greatest convexity below tlie uinlio. Kiglit valve 

 unknown. 



Hinge-line straight, somewhat anteiior : length greater tlian tlic length ol' 

 the valve. 



