Gasteropoda, MOLLUSCA. Iahtiiinid,^. S ' A'd 
thin and caducous, though in some of the northern 
species it is thick, hard, and persistent. The animals 
of this family are chiefly inhabitants of sandy and 
gravelly situations, ranging from low wafer to ninety 
fathoms; either burrowing in the sand near the lowest 
ebb of the tide, where their place of concealment is 
indicated by a small heap of sand, or in sand-banks far 
from shore. They are very voracious, not only boring 
into other shells by means of their elongate and 
retractile proboscis, but, as Dr. Gould informs us, de- 
vouring to a great extent the dead fish and other 
animals thrown up by the tide. The use of their large 
foot is here obvious, for by expanding it they can 
envelope completely the objects on which they pre}-. 
They in their turn serve as food for fishes, being 
devoured in great numbers by the cod and haddock, in 
the stomach of which animals they are often found. 
The recent species are numerous, upwards of one 
hundred having been described. They are widely 
distributed, from the Arctic seas, through Britain and 
the Mediterranean, to the Caspian ; and are found in 
numbers in India, China, Australia, South Africa, and 
the west coast of America, and the West Indies. 
Some of the species, as Natica herculea, from Sitka 
and the Oregon, attain a large size. The egg-cases of 
the Naticidce are very curious; the spawn being 
deposited in the form of a subspiral or concentric 
ribband or strap, rendered firm by agglutinated sand. 
Mr. Harvey describes the nidus of a British species, 
Natica {Neverita) monilifei'a, as firmly gelatinous, or of 
the consistence of gristle ; transparent or nearly so, 
slightly coated with fine sand, and in shape resembling 
the hoof of an animal. When dry, he says, they look 
not unlike pieces of thin Scotch oat-cakes. The sur- 
face is marked with little hexagonal spaces which 
define the eggs. Dr. Gould in his “ Invertebrata of 
Massachusetts,” describes a North American species as 
a mass of sand glued.together into the shape of a broad 
bowl, open at the bottom and broken on one side. 
The thickness, he says, is about that of an orange 
peel, easily bent without breaking when damp, and 
when held up to the light is seen to be filled with little 
cells, arranged in quincunx order, each of these cells 
containing a gelatinous egg with a yellow nucleus, 
which is the embryo shell. In the collection of egg- 
cases in the British Museum may be seen fine examples 
of these nidi of British, North American, and South 
African species. For a long time these curious pi'o- 
ductions were considered by naturalists as zoophytes, 
and described under the iiames of Flustra arenosa, 
Escliara lutosa, &c. Ellis looked upon them as recep- 
tacles for some sea insects. 
The opercula of the animals of the Naticidce, as we 
have already stated, are either horny or covered 
externally with a coat of shelly matter. This difference 
forms a good character for separating them into two 
large groups, the Naticina and Neveritina. The family 
is represented in Plate 1, figs. 1-3, by Stomatia halio- 
toideum, and fig. 4, Natica millepunctata. 
Passing the family Neritopsidce, the animals of which 
are unknown, and the species very few in number, we 
come to two larger and more interesting families; 
these are the Violet Snails and the Wentle-traps. 
Family — lANTHINIDHH {The Violet Snails). 
This family contains only one genus, lanthina. The 
animals belonging to it have a small flat foot which is 
furnished with a vesicular appendage on its hinder part, 
on the underside, which serves an important purpose. 
The shell is thin, translucent, and spiral, with a very 
small, sinistral nucleus. It resembles in shape that of a 
Helix, but is of a close vitreous texture. The aperture 
is large, somewhat quadrangidar, with a strongly- 
tw'isted columella, and a thin, sharp outer lip, notched 
at the outer angle. The species all partake, more or 
less deeply, of a violet hue — hence the name of the 
genus. The animals appear to be quite blind, having 
eye pedicels at the base of the tentacles, but no trace 
of eyes. As they seem, however, to select the night 
for their predatory operations on the high seas, •this 
deprivation can be of little moment to them. They 
are pelagic, that is, they are found floating about on 
the surface of the ocean, often in myriads, and appar- 
ently always gregarious. The apparatus by which 
they keep themselves constantly at the surface consists 
of the vesicular appendage to the foot mentioned above. 
This float, as it is called, is composed of numerous 
cartilaginous air-vesicles, and was ajitly called by 
Fabius Golumna, the first describer of the lanthina, 
Spurtia Cartilaginea ; the vesicles, says Dr. Johnston, 
being as trans[)arent as the air-bubbles in foam, while 
the skin is cartilaginous. “ Buoyed up on these air- 
bladders, the lanthina floats at ease, not left, however, 
to be driven at random by every current or breeze 
which may sweep across its path, for its course is 
guided by means of a small fin which runs along each 
side of the foot, a little above its edge. It is only when 
the ‘ tempest’s breath ’blows hard that the snail yields 
to its violence, and suffers wieck on the unfriendly 
shore.” — {Johnston.) This curious float is entirely 
secreted b}'^ the foot, and it has been found that when 
a portion is removed the injury is rapidly repaired. 
In addition to the use of this appendage as a float, it 
has been ascertained that the animal attaches its egg 
capsules to its under surface, suspending them there by 
little pedicels. It occupies a considerable time in the 
deposition of these eggs, and the capsules nearest to 
the extremity of the float are constantly found empty. 
The central ones contain young shells fully formed, 
and those nearest the animal are filled with eggs, “and 
it appears probable,” says Dr. Coates of Philadelphia, 
who has had opportunities of observing these creatures, 
“ that the young animals, when liberated from their 
chambers, ascend the float of the mother, and in this 
way gain access to the surface.” By some naturalists 
this float is considered to be an extreme modification 
of the operculum. It is much too large to be with- 
drawn into the shell, though some writers have sup- 
posed that the animal has the power of compressing it 
in such a manner as to make the shell sufficiently 
heavy to sink. All recent observers, however, assure 
us that these creatures have no power of sinking in the 
water. Dr. Bennett found on purposely irritating the 
animal, or even touching it in ever so slight a degree, 
that it withdrew itself within the shell, but had no 
