Marine Shells of Massachusetts. — 335 
have a single specimen found at Lynn, by Dr. Wm. 
Prescott, and have recently see 1 it, rarely occurring, 
at Portland, with the same station as in this harbour, 
and in company with Turbo x, al 
This species is referred, with some hesitation, to 
the genus Delphinula, on account of the following 
generic characters : shell subdiscoidal, depressed, 
broadly umbilicated ; spire slightly elevated ; whorls 
rounded, separated by a broad and deep suture ; aper- 
ture orbieular; margins perfectly continuous; oper- 
culum horny, thin, concentric, subspiral, orbicular, 
with concentric elements. The last whorl is also, as 
in all the species of this genus, much larger than the 
remainder of the shell. This species is, however, 
thin, destitute of raised or impressed markings, has 
the margins of the aperture thin, and is extremely 
small. The characters, which thus separate it from 
the other species of this genus, can scarcely be enti- 
tled to generic rank, unless subsequent examination 
should find a generic difference in the animal. 
Although this species is well figured by Montagu, 
and briefly described by this author and by Turton, I 
have thought that a new description of a species, 
which is the least of all our marine shells, not even 
excepting 7'urbo aculeus, and whose generic place is 
a matter of some uncertainty, would not be wholly 
without interest. 
Cerithium co pes mii Nob. Journ. of this Soc., 
Vol. IL. p. 284. This species is very nearly allied io 
the Murex tubercularis of Montagu, but differs: in 
several characters. The M. tubercularis has only 
