A. E. Verrill—Mollusca of the New England Coast. 437 
Cryptodon plicatus Verrill, sp. nov. 
Shell not very small, somewhat swollen, and rather thick for the 
genus; triangular-cordate in form, with very high and acute beaks, 
which curve forward but little. The anterior dorsal margin is 
nearly straight, but a little concave opposite the rather large, 
depressed lunular area; the posterior dorsal margin is broadly con- 
vex and rendered irregular by the strong plications of the margin ; 
the ventral margin is well-rounded, strongly angulated or lobed by 
the plications, and a little produced in the middle, in a line with the 
median ridge. The shell is remarkable for the unusual number of 
plications and undulations of its surface. Posteriorly there are two 
very large, much raised, sharply angulated plications, with a very 
deep concave depression between them, and a deep furrow between 
the hindermost and the edge of the shell; the second and larger 
fold is separated from a rounded or obtusely angulated median 
ridge by a broader concave depression. This median ridge is large 
and very distinct, and somewhat angular ventrally; farther forward 
there is a similar, but less marked, ridge, extending to the anterior 
part of the ventral margin. Anteriorly there is a very large, long- 
cordate, nearly smooth, concave lunule, which is bounded by two 
small, distinct posterior ridges, which are near together and run to 
the antero-ventral angle. The surface is covered by irregular and 
rather strong lines of growth, which become somewhat lamellose in 
crossing the strong plications. The hinge-margin is considerably 
thickened behind the beak, with a deep and conspicuous, curved lig- 
amental groove, back of which the edge becomes thin and flaring. 
The interior is angulated, corresponding to the exterior plications, 
and is marked by irregular radial strize near the ventral margin. 
Length of the largest specimen, 11"; height, 13""; thickness, 
Sur 
The largest and most typical example is a valve from station 2,193, 
N. lat. 39° 44’ 30”, W. long. 70° 10’ 30", in 1,122 fathoms (No. 44,825), 
A young living specimen, apparent identical, was taken at station 
2,205, in 1,073 fathoms (No. 44,826). 
This species is closely related to C. grandis V., but it has more 
numerous and more strongly developed plications; its beaks are 
more elevated and less curved forward, so that the form is more 
triangular; the ventral margin is less produced in the line of the 
median ridge; the shell also appears to be thicker and more swollen. 
