MOLLUSCOUS ANIMALS. 
137 
Natica quadrifasciata. 
Shell ovate, globose, solid, smooth, chesnut brown ; spire very short, conical ; last whorl with four 
narrow white spiral bands, hinder one broadest, extending up the spire ; throat purplish ; inner lip large, 
black brown. Axis largely umbilicated. Axis 1 J inch. 
Inhab. 
Natica cruentata. 
The front of the foot is produced, tentacles small, on the edge of a small cross membrane, with the 
mouth in a deep groove below it, between the tentacular ridge and the hinder edge of the front of the foot ; 
the penis very large, like that of Buccinum, with a small nearly terminal appendage, retracted into a cavity 
placed on the hinder side of the right tentacle. The operculum shelly. 
Natica melanostoma. 
The operculum with a distinct elevated spiral ridge in front. The muscle of attachment leaves an 
elongated scar on the pillar. 
SIGARETUS, Lam. CRYPTOSTOMA. Main. 
The animal of this shell only differs from Natica in being much larger in respect to the size of the 
shell, and in being provided with only a small ovate horny operculum. The size of the animal differs in the 
various species: thus in S. concavus it is capable of being withdrawn into the cavity of the shell, which is not 
the case with S. haliotoideus. 
MERRIA. 
The body spiral; the trunk proboscis-like, the tentacles conical, simple, with the eyes on their outer base; 
the foot small, rounded, with an oblong expansion in front, and a large triangular wing-like lobe on each side ; 
the edge of the mantle simple; the operculum very small, thin, just at the top of the foot. The shell white, 
naked. 
The pedal appendages of this genus are peculiar. 
Merria cancellata. 
Sigaretus cancellatus. Lam. 
NERITIN A. 
Trunk short, annulate, with a short fringe over the head ; a low elevatory ridge on each side of the body, 
from the back of the tentacula to the hinder part; the gills lanceolate, free, except at the base attached to the 
back of the left side of the respiratory cavity, and bent over towards the right side, formed of lamina united to 
labia. Eyes on short tubercles, free, but on the side of the base of the tentacles ; tentacles conical, separate 
vent on the right side of the branchial cavity. The muscles of attachment on each end of the columella, large 
and oblong. 
Perhaps this genus on account of the series of fringe on each side of the body should rather be placed near 
the Turbines. It is hermaphrodite like them 1 for I have not, in the many specimens I have examined, observed 
any with the male organ exserted. 
The lamina which separates the upper whorls of these shells is absorbed ; the mantle of N. Corona 
(when preserved in spirits) does not exhibit any process by which it forms the series of tubular spines. 
Several of the species live a long while out of water. 
T 
