Part 3

Arion subfuscus (i.e. somewhat tawny). Smaller (2 to 3 inches) than A. ater, grey or yellowish, with usually a dark stripe on each side. Foot-sole white, and its fringe white with dark cross streaks. Never very abundant.

Arion minimus.--The smallest Arion: not an inch long. Grey or yellowish. Feeds on fungi. Body wrinkled with microscopic spikes. Common. The young of A. ater might be mistaken for it.

Arion hortensis.--Grey with purple side bands. Foot-sole yellow. 1 to 1-1/2 inch in length. Generally found in gardens, as its name indicates.

Arion circumscriptus.--Very common in fields. A dark band down the back, foot-sole white. Very "sluggish."

Geomalacus maculosus (i.e. the spotted earth-mollusc).--Only found in south-west Ireland. Probably a relic of the prehistoric time when Ireland was joined to Portugal and Spain. Has a solid chalky shell beneath the shield. Blackish with oval yellow spots. Feeds on lichens.

Amalia gagates (gagates is Greek for "jet").--Dark lead colour. Foot-sole white. Length 2-1/2 inches. Local, and mainly near sea.

Amalia Sowerbyi.--Brown, speckled with black. Foot-sole yellowish. Length 2-1/2 inches. Local. Shell often very thick.

Limax maximus.--Length 4 to 6 inches. Grey with two dark lateral bands. Often found in cellars.

Limax cinereo-niger.--Ashy-black. Very like L. maximus, but with a sharp keel, and the sole paler in the middle than at the sides. Less nocturnal and less fond of houses; chiefly found in forests on hills. Local, and not common.

Limax flavus.--Yellow, with a faint dark network of markings. Tentacles blue. Sole cream. Length 4 inches. Only found in cellars and near houses.

Limax marginatus.--Semi-transparent. Grey, with two dark bands on each side. Foot-sole with a dark line down the middle. Shell solid, often a cube. Length 3 inches. Fond of tree climbing.

Limax tenellus.--Yellow. Tentacles black. Mucus yellow. Found in woods. Lives on fungi. Rare.

Agriolimax agrestis.--The common field slug. Swarms everywhere. Its milk-white slime is characteristic. Very variable in colour and markings.

Agriolimax lævis.--Slender. All chocolate brown. Length 3/4 inch. Shell may be seen through the mantle. Active. Our smallest slug. Usually found near ditches.

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It may be useful here to give the chief differences between the genera Arion, Amalia, Limax, and Agriolimax. The shield in the first two is granulated, in the other concentrically striated. The breathing orifice in Arion is in front of the centre of the mantle margin; in the others behind. The shell is distinctly formed in all but Arion, in which it is absent or represented by a few granules. Arion has no dorsal keel. Amalia has one all down the back. In Limax and Agriolimax it is confined to the caudal part. Other differences are only discovered by dissection.

One may also here note that to preserve slugs is difficult, and the best plan is to have a coloured drawing made of them when extended. Otherwise they may be drowned in cold water, cleaned of slime with a soft brush, and then preserved in glass tubes with diluted formalin or alcohol. Or, after drowning, they may be skinned and the skins dried on a card and varnished. Note also that most slugs have many variations in colour and markings.

Testacella haliotidea.--This genus of slugs forms a link between the naked slugs with rudimentary shells within, and the snails which live within their shells. The name Testacella, or little shell, was given by Cuvier in 1800, because this slug has a small shell at the end of the tail. Haliotidea means having a shell in the form of the marine shell Haliotis, the meaning of which again is the ear-shaped seashell, often called "Venus' Ear." It is subterranean in habit, and lives on worms. It should be looked for on the surface on damp nights, or is found when digging. Its length is 3 inches at most. Pale yellow in colour. See the illustration on page 35.

Testacella scutulum (a little shield).--Not so common as the former species, and differing chiefly in anatomy.

Testacella Maugei.--First found at Tenerife by M. Mauge. Reaches 4 inches in length. Deep brown in colour. Shell larger. Rarer and more western in habitat than the other species.

Vitrina pellucida.--The Vitrinas in several ways afford a connecting link between the slugs and snails, having the same tooth-formation and mantle as the former, while the shell cannot contain the whole body. As the name indicates, the shell is like a bubble of clear greenish glass and very delicate. It is small, and found in damp places, coming out mostly at night. Omnivorous, it is often found feeding on dead worms, and, unlike nearly all our earth molluscs, can be found abroad in winter.

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.