1S3 
PALAEONTOLOGY OP NEW-YOEK. 
Dorsal valve concave, the concavity less than the convexity of the 
opposite valve. The area is narrow, that of the dorsal valve being a 
bare line : the ventral area is twice as wide in the middle as near the 
extremities. Cardinal spines small, and usually but slightly oblique to 
the hinge-line, rarely more than two or three visible on each side of 
the beak. 
Surface marked by numerous slightly elevated rounded striae, a few 
of which are more prominent near the beak, and increase by bifurca¬ 
tion and intercalation till the number on the margin becomes from 
fifty-four to sixty or more. The striae towards the cardinal angles are 
less conspicuous, and sometimes from exfoliation are not at all visible. 
The entire surface in well preserved specimens is marked by extremely 
fine concentric striae. 
The cast is a little constricted within a line about two-thirds the 
length from the beak, the middle being more gibbous, while it is a little 
expanded beyond this line. The surface of the cast is punctate, moderately 
marked by striae, becoming more strongly marked at the constriction 
and from thence to the margin. The interior of the valve preserves 
similar markings, the surface being papillose or pustulose. The muscular 
impressions of the ventral valve are sometimes defined, and there is a 
median longitudinal ridge. The interior of the dorsal valve is pustulose 
in lines corresponding to the striae. The muscular impressions and base 
of cardinal process are not defined in any specimens observed. 
After an examination of a large number of individuals, I find the variation in 
number of strite too great to offer any reliable character for specific distinction. 
The species is doubtless the one figured by Mr. Vanuxem (loc. cit.); and I am 
disposed to believe that the Strophomena crebristriata* and S. lineata of Conrad 
(loc. cit.) may be the same species. It is most nearly allied to. C. yandellana, and 
may perhaps be regarded as identical with that species. There are, however, cer¬ 
tain differences which are constant in all the specimens examined. The C. lineata 
is always more gibbous ( See figs. 3/and 4 d, Plate 20) : in C. yandellana the cavity 
of the ventral valve is more regularly concave, and less distinctly constricted 
* I have already referred with doubt a species from the Schoharie grit to S. crebristriata of Conrad ; 
but since that description has been printed, I have had reason to question the correctness of my refe¬ 
rence. It is impossible to determine positively the species to which some of these descriptions refer. 
