32 AMERICAN MARINE CONCHOLOGY. 
Allied to B. Humphreysianum, but differs in its plicated and 
more convex whorls, deeper transverse sculpture and want of 
color. It might be taken for a thin and delicate form of B. undu- 
latum, but is easily distinguished by the number and straightness 
of the longitudinal plications of the spire-whorls, the more nume- 
rous and sharply-cut transverse ridges, and the wider mouth. 
5. B. HUMPHREYSIANUM, Bennett. Fig. 47. 
Zool. Journ., London, i. 398, t. 22, upper figures. 1825. 
Stimpson, Rev. of Buccinums, Canad. Nat. 1865. 
Buccinwm ventricosum, Kiener, Iconog. Buc., iv. t. 8, f. 7. 1841. 
(not of Lamarck.) 
Buccinum ciliatwm, Gould, Invert. Mass. 307, f. 209. 1841. 
(not of Fabricius. ) 
Shell rather below the medium size, very thin, translucent, pale- 
brownish, with fulvous or reddish markings, sometimes obsolete. 
Spire conic; whorls 7, somewhat flattened above and regularly 
convex below, so as to be faintly shouldered above the middle. 
They are neither plicated, carinated, nor angulated, and the sur- 
face is much smoother than in most species of the genus. The 
primary ridges are to be distinguished from the secondaries only 
at the obsolete angle or shoulder of the whorl, where there are 
generally two or three small ridges on each side of the more pro- 
minent ones and the corresponding sulcus. On the middle and 
lower part of the body-whorl, where the transverse ridges are for 
the most part equal in size and strength, and equal to the inter- 
vening grooves, the latter are crossed by well-marked though mi- 
croscopic lines of growth. The aperture is almost one-half the 
length of the shell and about three-fifths as broad as long. The 
outer lip is very little thickened and scarcely at all projecting 
below, and it has no sinus at the middle. Periostraca ciliated. 
Length 37, diam. 20 mill. 
Gulf of St. Lawrence, northwards ; Northern Europe. 
It may be recognized by its thin structure, superior flattened 
whorls, and the total absence of plications. 
Genus NASSA, Martini. 
Verzeich. e. Ausserl. Samml. 1778. 
Shell ovate, ventricose; body-whorl variously sculptured ; aper- 
ture ovate, with a short, reflected, truncated anterior canal; inner 
lip smooth, often widely spread over with enamel, with a posterior 
