and Shells of Massachusetts Bay. 101 
convex, concentric basal stri: scarcely perceptible, trans- 
verse strie very apparent ; umbilicus moderately wide and 
extending nearly to the apex; aperture circular, lip 
sharp, smooth internally, and slightly reflected upon the 
umbilicus. Interior iridescent; operculum thin, horny, 
concentrically spiral. 
Osservations. This shell has considerable affinity 
to T. cinéreus, but differs in being much less pyramidal 
in form, and in having a less turreted aspect, and is en 
tirely destitute of the strongly marked coste, which are 
So prominent on that species. "The revolving or concen- 
tric basal strie, instead of being, as in that, most appa- 
rent, are nearly imperceptible. It is altogether a much 
smoother and heavier shell, the color is entirely different, 
and its whole appearance renders it oe distinguish- 
able from either of the preceding species 
Considerable numbers were found in ide taken be- 
tween Marblehead and Nahant, but very few were in 
even a tolerably perfect state. I have considered it a 
species, upon careful examination of about fifty speci- 
mens, in which the differences pointed out between it 
and 'T. cinéreus were invariable. It may possibly ex- 
ist on the W. coast of Great Britain, and if it does, 
would probably be figured by Donovan, I have never 
seen his work. 
PYRAMIS STRIATULUS. 
Plate I. Fig. 6. 
P. testa parva, subulati, albidà, transversim tenuissimé striatá, su- 
turis impressis, aperturà ovatà, basi leviter effusa. 
Long. twelve twentieths, basal diam. four twentieths 
of an inch. 
