Our British Snails

by J. W. Horsley

Vitrea (Polita) lucida.—This is the largest of our British Hyaliniæ, which are difficult to distinguish. The body of this species is cobalt blue, the apex of the shell is flat, its colour opaque, and the last whorl more expanded than in others. All belong to the sub-genus Polita, and have polished or glossy shells. All love shade and moisture, and should be sought under stones or wood or in moss. They only come out by day when it is wet, a habit they may have acquired from their being a favourite food of birds, 416 having been found in the crop of one nestling Stockdove; while various flies are very destructive to them. This species prefers animal food, and is more gregarious than others. Not common.

Vitrea (Polita) cellaria.—The next largest species is the most common of all. It is fond of cellars (whence its name), and I found it under the stone lid of a manhole in the drain of S. Peter’s Rectory, Walworth—the only shell left in that part of London. It resembles the previous species, but is smaller and has a broader and deeper suture between the whorls, while the foot-sole is paler than the body.

Vitrea (Polita) Rogersi.—Local. Found in dense woods. It is much like both H. cellaria and H. alliaria, and all three smell of garlic, but the last is much smaller than the others. The tentacles in the first are long, and in the third short; while in Rogersi the upper pair are long and the lower very short. It is also the most glossy of all. If put in a box with other small shells it will clean them by cannibalism.

Vitrea (Polita) alliaria, i.e. smelling of garlic.—Often confused by quite good conchologists with the preceding species, but the body is much darker, and the shell smaller and less white below than either cellaria or helvetica. The always present smell is said to protect it from ants. Common, but local, and often a pest in greenhouses and ferneries.

Vitrea (Polita) nitidula.—Common. Less glossy. Marked expansion of the last whorl as it nears the mouth.

Vitrea (Polita) pura.—Like nitidula but smaller, and edge of mantle white instead of dark. More common in the north. Shell thin and dull white.

Vitrea (Polita) radiatula.—Never abundant. Striations on shell give it a radiated appearance when magnified. Animal nearly black.

Vitrea crystallina.—The smallest of the genus. Shell transparent, pearly white. Umbilicus (i.e. the opening in the centre of the underside showing the whorls) very narrow. Subterranean in habit. Whorls, four; whereas H. pura has five; also more compressed.

Euconulus fulvus.—Distinctively pyramidal in shape. Small. Brown. Common under rotten branches and moss in woods. Hardly hibernates.

Zonitoides nitidus.—Chocolate-brown, with no white round the umbilicus (as has H. nitudula). Larger than, but not unlike, H. radiatula. Gregarious. Chiefly found by water; also in damp hothouses. Amphibious.