Snail, the common name of the helicidoe, a large family of gasteropod mollusks, terrestrial and air-breathing. The number known is now so large that the treatment of the subfamilies and genera would require a volume. Restricting the name helicidoe to such as have a well developed external spiral shell, the snails may be characterized as animals breathing air by means of branchial vessels spread like a network over the internal walls of a cavity in the anterior part of the body, covered by the shell, and communicating with the atmosphere by a small valvular opening on the right side; they have four retractile tentacles, the upper two the largest and having eyes at the apex; there is a dentated horny jaw on the upper lip, which is opposed by the tongue; the gullet is wide, with large white salivary glands on its sides, and the liver is well developed; the whole body is very glutinous; the locomotion is slow, by means of the ventral foot; they are hermaphrodite, with reciprocal impregnation. The shells are always external,' vary much in form, and contain the entire animal; they have no operculum, the opening during hibernation being closed by a secretion from the mantle, which hardens into what is called the epiphragm; the shell is generally turned from left to right, the free edge to the right, but they are often reversed; the newly hatched young resemble their parents, and have a shell of one whorl and a half.

They are sensitive to cold, and like moist places; the sense of touch is acute, especially in the tentacles, and they appear to have a sense of smell; they are nocturnal, and feed principally on plants, though sometimes devouring each other. The reproductive season is toward the end of spring; the eggs, to the number of 30 to 100, are deposited in moist places, in natural or artificial holes; the young come out in 20 to 30 days. Snails are distributed very widely, from the northern limit of trees to Tierra del Fuego, from the hot and moist plains to a height of 11,000 ft. on mountains; some are cosmopolite, ranging wherever their food is found, and others are restricted within narrow limits. About 1,500 species have been described, some of which from their voracity are very injurious to vegetation, and some useful to man as food; they are very tenacious of life, and able to resist long droughts. A specimen of the desert snail of Egypt (helix desertorum), which remained dormant in the British museum four years, afterward lived in the possession of one of the curators more than two years. - The genus helix (Lam.) is the type of the family.

The Roman or vineyard snail (H.pomatia, Linn.) is a large species, reddish brown with paler bands; these snails were used as food by the ancient Romans, who reared them in parks, and fattened them on cooked meat and flour, obtaining them from the islands of the Mediterranean; they are still eaten in many countries of Europe, especially by Roman Catholics during Lent, being considered as fish; great numbers are eaten in France; they are also recommended as an ingredient in soups for consumptive persons. The reproductive internal organs, in the apex of the shell, consist of many parallel caeca, each of which has an external layer producing eggs, and an internal sac producing semen; the apparatus is very complex. The H. aspersa (Linn.), or common garden snail, originally from Europe, but now naturalized in most parts of the globe, is also used as food, when boiled in milk, for consumptives. These species when abundant are very destructive, laying waste whole gardens in a single night, always attacking the tenderest and most succulent plants; besides their natural enemies, mammals and birds, great numbers are killed by fires, inundations, sudden changes of temperature, felling of forests, cultivation of the land, and by hogs and poultry following the plough; the remedies for their depredations are the same as for the slugs.

The largest of the American snails is the H. albolabris (Say), of a yellowish horn color, with white, broadly reflected lip; the shell has five or six whorls, with minute revolving lines and the umbilicus closed; in October they cease feeding, and select a place under some log or stone, where they fix themselves for the winter, mouth upward. For details on the American species, see Dr. A. Binney's "Terrestrial Air-breathing Mollusks of the United States" (3 vols., Boston, 1851, and vol. iv., a continuation by G. W. Binney, Boston, 1859).

American Snail (Helix albolabris).

American Snail (Helix albolabris).