TÆNIA, in zoology, a genus of insects, belonging to the order of vermes zoophyta; the body of which is of an oblong form, and composed of evident joints or articulations, in the manner of the links of a chain, with a mouth and viscera in each joint; so that the joints, which are exceedingly numerous, are in some measure so many distinct animals, and can live independent of each other. There are four species; the solium, or tape-worm, is found in the bowels of men, and fishes, and frequently extends to many yards in length. See MEDICINE, p. 160.