104 Couthouy's New Species of Mollusca 
Conchology of the British Islands, have described any 
thing like it. 
PrLEUROTOMA BICARINATA. 
Plate I. fig. 11. 
P. testi perparvà, fusiformi, turrità, fusco-nigricante, transverse 
striata et sulcatà; suturis impressis; anfractibus convexis, medio bi- 
carinatis; apertura ellipticà ; labro crenulato, caudà brevi, sinu min- 
Pi. eleven fortieths, diam. of last whorl two fortieths 
of an inch. 
Habit. waters of Mass. Bay. 
Cabinet of Bost. Soc. Nat. History. 
Description. Shell fusiform, turreted, color an uni- 
form dark brown ; whorls six, convex, having numerous, 
slightly elevated, revolving ribs, with intervening strie 
upon the lowest, and impressed in their middle portion 
by a deep sulcus, which forms a distinct revolving cari- 
nation upon each side of it; sutures clearly defined ; 
body-whorl half the entire length of the shell; strie of 
growth very minute ; outer lip thin, sub-arcuated, serrated 
on its margin by the terminating strie; the sinus at its 
juncture angular, very slight, and hardly amounting to a 
fissure ; columella arcuated at its superior third ; aperture 
elliptical, terminated by a short canal slightly inclining to 
the left. 
Osservations. This little species must be extremely 
rare, as | have never been fortunate enough to obtain 
more than a single specimen, which was taken from the 
maw of a haddock, caught about three miles east of Na- 
hant, in July last, and is happily perfect. 
The sinus is but slightly indented, but the incremental 
strie plainly indicate that it has Been constant, a 
