AMONG the fish we meet with in the seas of the Antilles of America, we find, that this I am going to describe will appear precious, from the beautiful purple colour it produces, in the same manner, that the cuttle-fish produces its ink, if a means could be found to procure this liquor in a sufficient quantity to render it an article of commerce. These fishes are soft, viscous, without shells, scales, or bones; are of the nature of the _polypi_, and such other kinds, without feet, fins, or any thing to supply their places. Their motion is vermicular; and, like the slugs, they wreath themselves up, and when touched make themselves quite round. They fill up certain membranes of the body with water. Their local motion; _antennæ_, which they lengthen and contract; and a great many other properties, which they have in common with snails, slugs, and turbinated shell-fish, made me call them naked snails: and altho’ they have not the most essential qualities of snails, I thought I might give them the name; for they have no particular appellation in this country. Some call them piss-a beds, some sea-cats, and others a less modest name, _tapecon_, taken from Pliny. The Negroes and country people disagree upon this subject; and therefore I thought all their names ought to be rejected, in order to adopt a more significant one, which I have given them; and that altho’ they are without shells, a quality essential to snails, they had a right to that class by their other properties and qualities. This fish is commonly four inches long, and two thick; of a greenish colour, spotted with black, each of which forms a circle. The under part is like that of snails, flat, with kinds of _mamillæ_, or rugosities, which are adhesive; by means of which they advance in a vermicular motion; and when touched become round, by retracting their neck and head; and afterwards protrude them considerably, according to their motion and progression, crawling upon rocks to seek their food. The head of this animal has a flatness, or is inclinable to a square or parallelogram. On each side there are membranes or skins, which form kinds of ears; and under them others, which at times fill with water, and are then transparent. Under this thick skin there is a _cranium_, of a kind of coriaceous or cartilaginous matter; and in the _cranium_ we find the brain, which is a white substance, and very firm. At the basis of the head its oval wide mouth is placed, being above two lines long, which often discovers a white hard edge, with which he crops the fucus’s, and other sea-plants, for his nourishment.