in zoology; a genus of insects of the order of Vermes mollusca, the characters of which are: The body fixes itself by its tentacula, is oblong, and rather tapering; there are two ovaries like tails, and the tentacula are shaped like arms. (See three specimens figured on Plate CCLXXIV.)—1. The cypri- nacea has four tentacula, two of which are lunulated at the top. It is a small species; about half an inch long, and of the thickness of a small straw; the body is rounded, of a pale greyish white, glossy on the surface, and somewhat pellucid; it is thrust out of a kind of coat or sheath, as it were at the base, which is of a white colour and a thick skin; towards the other extremity of the body, there are three obtuse tubercles, one of which is much larger than the rest; the mouth is situated in the anterior part, and near it there are two soft and fleshy processes; and near these there is also on each side another soft process, which is lunated at the extremity. It is found on the sides of the bream, carp, and roach, in many of our ponds and rivers, in great abundance. 2. The salmoncea, or salmon-louse, has an ovated body, cordated thorax, and two linear arms approaching nearly to each other. 3. The aeolina, has a lunated body and cordated thorax; and inhabits the gills of the cod-fish and ling of the northern ocean.