the Slug, or Naked Snail; a genus of insects belonging to the order of vermes mollusca. The body is oblong, fitted for crawling, with a kind of molecular coat on the upper part; and the belly is plain. They have four tentacula, or horns, situated above the mouth, which they extend or retract at pleasure.—This reptile is always destitute of shell; but besides that its skin is more clammy and of a greater coarseness than that of the snail, the black naked slug has a furrowed cloak, almost as thick and as hard as leather, under which it withdraws its head as within a shell. The head is distinguished from the breast by a black line. It is in its head and back that the snailstone is found; which is a small pearly and sandy stone, of the nature of lime stones: according to a popular opinion, it cures the tertian ague, if fastened to the patient's arm. These slugs move slowly, leaving everywhere clammy and shining marks of their passage. Their coming together is towards the end of spring. The organs of generation are placed, as in the snail, on the right side of the neck. The male implement unfolds with the same mechanism as the finger of a glove when turned inside out. They are sometimes met with hanging in the air with their heads downwards; and their tails, united by a kind of viscous and thick tie, grappled to the branch of a tree. In this situation they remain for three hours, and that is the time of impregnation. They deposit their eggs in the earth. There are eight species, distinguished entirely by their colour; as the black slug, the white slug, the reddish slug, the ash-coloured slug, &c. The black slug is hermaphrodite, both sexes being in each individual, and in the coitus both impregnate and are impregnated at the same time.—A black slug powdered over with snuff, salt, or sugar, falls into convulsions, casts forth all its foam, and dies. See Reproduction.