380 MARINE INVERTEBRATES 
of Dolium, except that it has two side-flaps, which, when extended, 
partially inclose the shell. The shell is thin, with an almost flat spire 
and a greatly enlarged body-whorl. The aperture is flaring, and is 
drawn out anteriorly into a tapering canal, which gives to the shell the 
outlines of a pear. The ornamentation is revolving, but not high} 
raised, and there are ribs with very distinct longitudinal lines of growt 
between. The color is pure white, or sometimes yellowish, with rufous 
spots; within it is golden. This attractive shell is usually from three 
to four inches in length, but is sometimes found considerably larger. 
(Plate LXXI.) . 
FAMILY CASSIDIDE 
Genus Cassis 
The cassides, commonly known as the “ helmet-shells,” are car- 
nivorous mollusks, which lead an active life in sandy stations, 
prowling about in search of bivalves, upon which they prey. 
They have a large siphon and a fairly large and extensible pro- 
boscis. The footis broad and strong, being well adapted for plow- 
ing through the sand. The shell of Cassis is large, generally 
heavy and inflated, with a short spire and a short, recurved ante- 
rior canal. The lip is much thickened. Upon the Atlantic coast 
of North America there are four species of Cassis. They are all 
properly West Indian in their faunal relations, but have found 
lodgment on the American shore at various points. All of them 
have been taken in the neighborhood of Cape Hatteras, two of 
them in West Florida, and two in Texas. 
C. tuberosa. A large, heavy shell, often from six to eight inches in 
length, with a flattened spire. The aperture is long and narrow, with 
large white teeth upon the outer lip, which is also greatly thickened. 
The columellar lip is ribbed. A heavy deposit of enamel to the left of 
the columellar lip gives the shell a triangular outline. A row of very 
large nodes upon the shoulder of the body-whorl and two rows of obso- 
lete nodes below are characteristic features of this species. The color is 
light yellowish-brown suffused with pink. The aperture and the columel- 
lar callosity are flesh-tinted, with chestnut trimmings. The anterior canal 
is deep and recurved. 
C. cameo. A species of about the same size as the last, but more 
ovate or ventricose in form. It is coarsely striated, with elevated growth- 
lines, and has circling rows of large, rib-like elevations, having some- 
times nodes upon the body-whorl. The columella is conspicuously 
ribbed and greatly expanded. The outer lip is thickened, and has 
lamelliform teeth within. Flesh-colored; teeth white; purple-brown 
trimmings. A great many of these shells are sent yearly from Nassau 
