348 Descriptions of some Shells, &c. 
tinct arcuation in advance of the angle: remaining portions of the 
contour quite regularly rounded: teeth, small, curved forward, point- 
ing toward the anterior-basal margin, and supported, in each valve, 
by a thin and elevated rib: muscular and palleal impressions very 
indistinct. 
Length, 0.64 of an inch. 
Height, 0.50 do. 
Thickness, 0.28 do. 
There is reason to believe, that a larger size is sometimes attain- 
ed. Smaller individuals have rather greater proportionate length. 
Inhabits muddy bottom, Newport harbor, R. I. Obtained by the 
dredge from a depth of about fifteen feet. The ossiculum of this 
species, Fig. 1, d, (two views of the same enlarged) is small but 
stout: it is attached, anterially, by the ligament, to the spoon-sha- 
ped teeth. 
On comparing the figures above referred to, with shells in the 
Philadelphia Museum, referred to by Mr. Say, Mr. Conrad is of the 
opinion, that this is the A. papyratia. In deference to this authori- 
ty, and inclining to the same opinion, I affix Mr. Say’s name—giv- 
ing the figures because, as I think, no figure has been given by Mr. 
Say. At the same time, I am bound to remark that, in some par- 
ticulars, the description published by that naturalist, (see Journal of 
Nat. Sciences, Phil., Vol. I, p. 314) does not well agree with our 
shell. He says, for instance, of the papyratia, “one valve very 
convex,” while in this, the inequality of the valves is scarcely pe!- 
ceptible—and he gives a greater proportionate length (‘ width” of 
Say) than I have ever noticed amongst ours. Should this prove @ 
different species, I suggest the name of A. fragilis. 
Genus Astarte, Sow. 
A. castanea? Say. Fig. 2, a, b, c,d, e, f. 
Variety B. 
Shell, sub-oval or sub-orbicular, length not exceeding the height, 
thick and heavy, inequilateral, with prominent beaks: umbones, 
rather convex: disk, with minute concentric wrinkles, deeper on the 
posterior slope, and a few obsolete undulations: epidermis, brown- 
ish-yellow, generally quite light, sometimes with a few darker zones: 
cartilage-slope, curved: posterior margin, sub-truncated: lunule 
and corselet, excavated and lanceolate: within, white, sometimes 
with a faint bluish tint: cavity, rather small; inner margin, regular- 
