344 PALEONTOLOGY OF NEW YORK. 



Strophomena Conradi, sp. nov. 



PLATE IX A, FIG. 3 ; AND PLATE XX, FIGS. 3-2, 33. 



Shell semiovate in outline ; hinge-line straight and forming the greatest 

 diameter of the shell. Cardinal area narrow on both valves; broader on the 

 pedicle-valve and but slightly elevated at the umbo. Delthyrium covered ; 

 deltidium perforated at the apex. Pedicle-valve convex in the umbonal 

 region, but becoming deeply depressed and concave over the middle of the 

 shell and again elevated about the margins. The depression of the valve is 

 most conspicuous along the median line and on the anterior margin where it 

 produces a subnasute extension. The brachial valve is flat or slightly con- 

 cave at the umbo, becoming convex over the pallial region ; it reaches its 

 greatest convexity at about the middle of the shell and is thence deflected 

 gradually in the median line and more abruptly on the lateral slopes. 



Surface of the shell covered with radiating striae, arranged in fascicles 

 of 4 to 7 fine ones between each pair of coarser ones There are no con- 

 centric rugsB on either valve, but the radiating stria3 are crossed by ex- 

 ceedingly minute concentric lines. 



Width of the original specimen along the hinge, 23 mm. ; greatest length, 

 19 mm. 



Trenton limestone. Jacksonburg, N. Y. 



Strophomena Winchelli, sp. nov. 



1883. Strophomena nutans. Hall. Rept. State Geolog^ist N. Y. for 1882, expl. pi. (ix) 39, figs. 10, 12-14. 

 PLATE IX, FIGS. 10, 12-U ; PLATE XX, FIG. 26. 



Shell elongate semiovate ; strongly convexo-concave. Hinge-line straight and 

 making the greatest diameter of the shell. Cardinal angles sometimes ex- 

 tended. Pedicle-valve with a moderately broad area arid deltidium; apex 

 slightly elevated, the valve becoming deeply concave over the pallial region 

 and reflected at the margins. The teeth are strong and divergent, and from 

 their bases extend elevated curving ridges which form the margin of the 

 subcircular or subovate muscular area. Diductor scars broad, enclosing an 



