Testacellid.e.- 



-MOLLUSCA.- 



-Helicid.e. 



353 



islands. During tlio dry season in hot climates tliey 

 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 smface of the contracted 

 animal. This is the only operculum possessed by this 

 Older 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 Geoi'iiila — 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 Limnopiiila — 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 expanded tentacles. These form 

 the TllALASSOPlliLA — 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 fiimilies. Our limits will not allow us 

 to do more than take up the leading and most typical 

 of these. 



Family-TESTACELLID^. 



This family is rather interesting. 



The genus Testacellos 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, suhspiral, 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 

 Bull, and feeds upon worms. The common earth- 

 worm is its especial prey, and this it is said to swaflow 

 whole. 



The genus Oleacina (:= Gkindina) differs from 

 TiStacellus 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. 

 Tlie animal is twice the length of the shell, and, like 

 the Tcstacellus, is carnivorous and predaceous in its 

 habits, attacking other Molluscs as large as itself with 

 avidity, and devouring them. The mouth is probos- 

 cidifonn and furnished with elongate tentacles. 

 Vol. II. 



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 Nanirue are numerous in species, Dr. 

 PfeitTer 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 au external well developed, spiral 

 shell, as the Helices. 



Genus Limax. — See Plate 6, fig. 1 {Limaxflcivus). 

 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 reaUy very great. 

 Topical remedies are here of little use ; the numbers 

 of the host and the extent of their field, their tenacit" 

 of life and mode of concealment, render suoh 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, iu 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 obhque, 



3 Y 



