Testacbllid^.- 
MOLLUSCA. Helicidas. 353 
islands. During the dry season in hot climates they 
retire into hiding-places, where they remain torpid till 
moisture again brings them forth. While in this state 
of torpidity or “ estivation,” as it is called, the mouths 
of the shells are covered with a temporary lid called the 
epiphragm, which is formed by the hardened juices of 
the body moulded on the surface of the contracted 
animal. This is the only operculum possessed by this 
order of Molluscs. The Pulmonata vary much in 
their habits, and upon this account they have generally 
been divided into three groups : — 
The first group live upon dry land. Their eyes are 
placed on the top of a lengthened cylindrical foot-stalk. 
The tentacles are cylindrical, shorter, and lower down 
than these eye-peduncles, and are sometimes very small, 
occasionally wanting. These form the Geophila — the 
Terrestrial group. 
The second group are inhabitants of fresh water, 
coming to the surface, however, to breathe. They have 
their eyes sessile at the base of the tentacles, which 
are subcylindrical or flattened, and simply contractile. 
These form the Limnophila — the Fresh-water group. 
The third group are inhabitants of salt marshes and 
places near the sea. Their eyes are sessile also, and 
are situate on the fore part of the frontal disk, formed 
by the flattened and •••xpanded tentacles. These form 
the Thalassophila— the Marine group. 
Geophila — Terrestrial Snails. — By far the 
larger number of the species of this order belong to 
this group. They vary much in form as well as in 
general habits, and being very numerous, have been 
divided into a great many genera, and form indeed 
several distinct families. Our limits will not allow us 
to do more than take up the leading and most typical 
of these. 
Family— TESTACELLIDiE. 
This family is rather interesting. 
The genus Testacellus or Shell-slug as it is 
called, is remarkable for the shape and position of the 
shell. The animal is of considerable size, lengthened, 
produced in front, with a groove on each side of the 
back. The shell is small, ear-shaped, siibspiral, with 
a wide aperture, and is placed on the hinder end of 
the animal’s back. — See Plate 6, fig. 1 {Testacella 
Maugeri). Only two species are known — one a native 
of the south of France, and the other of the island 
of Teneriffe, but both are now naturalized in England. 
The animal is carnivorous in its habits, burrows in the 
soil, and feeds upon worms. The common earth- 
worm is its especial prey, and this it is said to swallow 
whole. 
The genus Oleaci.va (= Glandina) differs from 
Testacellus in the form of its shell. It is of an oblong, 
fusiform shape, with a narrow, elliptical aperture, a 
sinuated outer lip, and an arcuately truncated colu- 
mella. The surface is generally smooth and shining. 
The animal is twice the length of the shell, and, like 
the Testacellus, is carnivorous and predaceous in its 
habits, attacking other Molluscs as large as itself with 
avidity, and devouring them. The mouth is probos- 
cidiform and furnished with elongate tentacles. 
VoL. II. lOI 
The species of Oleacina are numerous, and by far 
the greater number are American, either inhabiting the 
continent itself or the large islands in its vicinity, as 
Cuba, Jamaica, &c. They are generally found living 
on the bushes in the vicinity of the sea. 
The genus Nanina has a large, external, exposed 
shell, which in general is light, thin, and polished. 
The shell is difficult sometimes to distinguish from that 
of the true Helix. It is depressed, smooth below, and 
has the mouth lunate, with its peristome (or edge of the 
aperture) of the same thickness as the shell, sharp, and 
not reflexed. The Nwiince are numerous in species. Dr. 
Pfeiffer enumerating no fewer than one hundred and 
eighty-nine. They are all natives of tropical countries, 
coming almost entirely from the continent of India, the 
large islands belonging to it, the Philippine islands, and 
the Moluccas. They inhabit thick, shady woods, and 
crawl with great vivacity among the leaves. 
Family— HELICID^. 
The animals of this family are destitute of the gland 
at the extremity of their foot. The tentacles are long 
and retractile under the skin, and the eyes are placed 
on their tips. Like the last family, some of the species 
have an internal, rudimentary shell, as the Limaces ; 
while others have an external well developed, spiral 
shell, as the Helices. 
Genus Limax. — See Plate 6, fig. 1 {Limax flavus). 
The true Slugs are of an elongated, sub-cylindrical 
form, and the shell is flat, oblong, not spiral, covered 
with a thin epidermis, and completely inclosed within 
the mantle. Upwards of thirty species of Slugs have 
been described, and they are found in greatest abun- 
dance in the temperate countries of Europe. They 
choose for their residence damp situations, hiding during 
the day under stones, and sallying forth in the evening 
to seek their food. This consists almost entirely of 
vegetable matters ; and as these creatures are gre- 
garious in their habits, they often inflict great damage 
on gardens and orchards, and even open fields. 
The most destructive species in this country are the 
Grey Slug {Limax agrestis), and the Black Slug {Limax 
ater). “You cannot look over the agricultural reports 
in our newspapers,” says Dr. Johnston, “ without seeing 
frequent notices of the ravages of these apparently 
insignificant creatures ; and the damage they annually 
do to corn, clover, and turnips, is really very great. 
Topical remedies are here of little use ; the numbers 
of the host and the extent of their field, their tenacity 
of life and mode of concealment, render such means 
nugatory, or at least of very partial benefit.” The best 
remedy in gardens and small plots of ground is the use 
of lime, either by placing lines of quicklime round the 
beds and borders, or by watering the ground with lime 
water. 
Genus Helix. — The True Snails have the mantle 
edge inclosed within the edge of the shell. The shell 
itself is globular or convex, with a short spire, and the 
last whirl larger than the others, composing, in fact, the 
greater portion of the whole shell. There is generally 
an umbilicus; but, in many instances, it is covered over. 
The aperture is regular, transverse, and is either oblique 
