Now let us enumerate the species of land and freshwater shells to be found, (all but two) in England, and most of them in Ireland or Scotland.
_Arion ater_ is a large (3 to 5 inches) and common slug, usually black (whence its name _ater_), but also red, brown, or white. In some varieties the foot-fringe is orange. When irritated it contracts into a hemispherical lump. A few chalky granules under the mantle are the representatives of a shell. See the illustration of three specimens on p. 31. That hole in the mantle is the breathing orifice, and its forward position is a characteristic of the group _Arion_. The body of slugs is kept moist by a constant exuding of slime from a gland in the tail.
[Illustration: Three specimens of _Arion ater_, showing tentacles, breathing orifice, and slime gland.]
_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.