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PALAEONTOLOGY OP NEW-YORK. 
Productella lachrymosa. 
PLATE XXV 
Strophomena lachrymosa : Conrad, Jour. Acad. Nat. Sciences Philadelphia, Vol. viii, pa. 256, pi. 11, f. 9. 
Shell ovoid or subhemispheric, semielliptical in outline; the propor¬ 
tions varying from nearly equal length and breadth, to width nearly 
once and a half as great as the length : hinge-line equalling or less 
than the width of the shell; extremities angulated or rounded. 
Ventral valve varying from moderately gibbous to very ventricose; 
the umbo sometimes a little elevated above the hinge-line and often 
extremely elevated and incurved, often flattened in the middle, more 
or less regularly arching from beak to base, abruptly depressed at the 
sides of the umbo, and spreading into more or less expanded ears, 
which are usually deflected, and rarely extend beyond the width of 
the shell below : basal margin regularly arched, or sometimes nearly 
straight in the middle. 
Dorsal valve moderately or more deeply concave, following in some 
degree the curvature of the opposite valve. In some specimens it is 
nearly flat in the upper and middle portions, and abruptly deflected 
at the margin. 
Surface of ventral valve (where the shell is partially preserved) marked 
by fine concentric striae, and, upon the ears, by strong concentric 
wrinkles, which become obsolete or are but faintly marked on the 
body of the shell. There is a row of four or five round spines rising 
from a little below the cardinal margin on each side of the beak; and 
surfaces of the casts are marked by numerous slightly elongate spini- 
ferous tubercles, from which rise somewhat slender spines. These spi- 
niferous tubercles are sometimes principally arranged in lines along 
partially continuous ridges. The dorsal valve is strongly wrinkled on 
the hinge-line, and sometimes these marks are continued across the 
valve in considerable strength; but the specimens examined do not 
show spine-bases. The casts or impressions of the exterior show pus¬ 
tules which indicate fossets on the exterior surface of the shell. 
