36 SHELLS OF NEW ENGLAND. 
This species is distinguished from the young of 
T. erosa by its much more convex whorls and prom- 
inent ribs. 
Cacum PULCHELLUM, St., Pl. II. f. 3. Bost. Proc., Oct. 
1851. Shell in its adult state clavate, .1 inch in 
length and .025 inch in breadth at its broadest part, 
arcuated, contracted at both extremities, and having 
a somewhat angular appearance at its outer or dor- 
sal outline, which is much longer than the inner. It 
is somewhat thick and strong, of a pale yellowish- 
brown color, and sculptured with about twenty-five 
strong rounded ribs, broader anteriorly, but narrow- 
er posteriorly, than their interspaces, not project- 
ing sharply beyond the outline of the shell, but giv- 
ing it a waved appearance. Operculum multispiral, 
of about eight volutions, corneous, and concave on 
the outer surface. 
The animal agrees nearly with the English species, 
C. trachea, as described by Mr. Clark. The head 
projects but little in advance of the foot, which is 
short. ‘The muzzle is cleft and transversely wrinkled, 
and has two black spots above just in front of the 
tentacule, which are thick, curved, and covered with 
large vibrille. The eyes are conspicuous, black, oval, 
and situated at nearly the middle of the bases of the 
tentacule, a little toward the inner sides. The oper- 
culigerous lobe projects a little beyond the operculum. 
In keeping alive several individuals of this species 
from April to November I observed the following 
stages of growth: — 1st. A slender, thin, areuated form 
