366 
PALAEONTOLOGY OF NEW-YORK. 
ChENUS CYPRICARDIMA (n.g.). 
There are a few species of shells in this group of strata which have the 
general form of Cypricardia ; being very inequilateral, -with a more or 
less distinctly defined oblique posterior ridge, the umbones anterior or 
subanterior and little elevated. The surface is concentrically grooved, 
or more or less distinctly marked by prominent ridges or imbricating 
lamellae, and, on some of them, these lamellae are radiatingly striated or 
cancellated. A single well-preserved specimen shows no external liga- 
mental area. In some species, the postero-cardinal margin becomes alate 
or subalate. They bear some general resemblance to Modiolopsis; but the 
shell is apparently thicker, and is more strongly marked by concentric 
striae and with a less conspicuous anterior muscular prominence, while 
the aspect and general expression of the shells are quite distinct. 
Until something more definite is known of the hinge-structure, I propose the 
above name as a provisional one for the convenience of designation. 
Cypricardiiiia lamellosa (n. s.). 
Plate XLIX A. Fig. 1 a , b, c. 
Shell subovoid, gibbous : umbones slightly elevated; anterior extremity 
abruptly rounded and extending little beyond the beak, somewhat 
contracted on the base anterior to the middle, with an undefined 
depression extending thence nearly to the umbones; posterior slope 
prominent, with a scarcely defined ridge ; cardinal margin compressed, 
obliquely subtruncated above and rounded towards the base. 
Surface marked by strong elevated distant lamellae ; the surface of each 
one showing, under a magnifier, distinct radiating striae, and sometimes 
another set of striae cancellating the first. 
Fig. 1 a. A specimen, natural size. 
Fig. 1 b. The same enlarged to nearly three diameters. 
Fig. 1 c. Cardinal view of the same enlarged. Another specimen examined is about twice 
the size of the one figured, or equal to two-thirds the size of figs. 1 b and 1 c. 
Geological position and locality. In the shaly limestone of the Lower Helderberg 
group, associated with Spirifer , Rhynchonella and Atrypa : Albany county. 
