270 Marine Shells of Massachusetts. 
is more common than the P. carica. At Nantucket 
both species are more common than at New Bedford. 
In Rhode Island they are said to be abundant. At 
Nantucket I have found two or three individuals, living 
on a muddy bottom below low-water mark. William 
H. Taylor, Esq. of New Bedford, recently showed me 
a number of specimens, which had been taken in the 
` pots set for lobsters. 
In the P. canaliculàta, the cronulatiolil which La- 
marck notices upon the carination of the whorls, are 
often obsoleté in the older specimens, in consequence of 
a decay of the external surface of the shell during the 
life of the animal. The labrum is broadly covered with 
a thin coat of polish, the outer limit of which is abruptly 
defined. The color is pale cinereous, brown, or whitish. 
The color of the fauces varies from chocolate brown to 
brownish yellow. Sometimes the inner margin of the 
labrum is whitish, A specimen in my cabinet.is.7 
inches long and 4 inches broad, a common size. 
The epidermis is strongly hirsute upon the upper 
whorls and upper portion of the body whorl, and be- 
comes less hirsute in receding from the carination down 
to the cauda. The hairs, which are quite sharp and - 
stiff, are arranged upon fine longitudinal elevated strie, 
distances which are regularly measured by transverse 
ri. "These hirsute lines, viewed transversely to the 
axis of the shell, are often alternately larger and smaller. 
They are more distinct longitudinally, and the longitu- 
dinal strie are also more conspicuous on the epidermis, 
but the transverse strie are more so upon the shell. 
The epidermis i is usually worn off from e upper v" 
, of the spire. 
