P d 
4 
278 Marine Shells of Massachusetts. 
common at Nantucket, but is rarely found at New Bed- 
ford. In the harbor of the latter place, under. a depth 
of three feet water at the time of low tide, P found a 
valve of the Pecten concéntricus, loaded with Serpule 
and the Vérmetus lumbricàlis, on the inner surface of 
which was an immature specimen. It occurs rarely. at 
Chelsea beach, where I once. found a single — 
without the animal, in the sa 
C. fornicata, Bn Anim. sans Vert. in loc. Pa- 
télla fornicüta, Linn. Syst. Nat. ; De Rorssy, Burr. 
Moll. V. 938. Crepidula fornicita? ? var. Say, Journ. 
Acad. Nat. Sc. II. 225. 
The large species of Crepídula, which grows on our 
shores, was described as a variety of the C. fornicáta 
by Say, who remarks that it may probably be distinct, 
as it seems to differ from the species as described by 
Roissy, in having literal lineations- instead of spots. 
Without attempting to decide upon the identity of the 
species, it may be remarked that the rufous lines are 
often interrupted and irregular, presenting the appear- 
ance of spots rather than of lines. "The prevailing sys- 
tem of coloring, however, is of waving rufous or chestnut 
colored lines, on a ground-of white, which is tinged more 
or less with the same or with a dingy blue; sometimes 
the surface is of a uniform chestnut color. The dia- 
phragm is a pure porcelain. white. The interior is of 
a chestnut color ‘sometimes uniform) more frequently i in 
- large irregular sf with white. "The convexity varies 
dividuals i it exceeds the breadth, 
A large om 5 in my cabinet is 2.18 i in. in length, 
and 1.37 in. in breadth. 
