Snail

Snail is the name of one of the best known members of the Gastropoda (q.v.), one of the classes of the Mollusca. The snails are well known, as they are widely distributed, and usually very abundant, and as they live on land. The name is often used in a general sense for all the molluscs with a shell (composed of a single shell) which live on land; it is, however, more correctly restricted to those belonging to the genus Helix. The "Watersnails" include species belonging to the genera Planorbis, Lymnaea, Paludina, etc. The snails have a coiled, spiral shell, whieh is often prettily ornamented by colour bands; they live on trees, grass, and under stones, etc., and are especially abundant in limestone districts. The animals feed on vegetable material, which they cut up by means of a long-toothed ribbon, or saw-like tongue, known as the "radula." They are active during the summer, and hibernate in winter, when the mouth of the shell is closed by a thin gelatinous film known as the "epiphragm." The animals are hermaphrodite, but always pair with other snails, and self-fertilisation never occurs. The snail is a very useful type in biology. The largest living species in England is Helix pomatia, the edible or Roman snail.