in zoology, a genus of insects belonging to the order of vermes intestina. The body of the ascaris is cylindrical, filiform, and tapers at both ends. The species are two, viz. 1. The vermicularis, with faint annular rings, and the mouth transverse, is about a quarter of an inch long, and thicker at one end than the other. It is found in boggy places, in the roots of putrid plants, and very frequently in the rectum of children and horses. It emaciates children greatly, and is sometimes vomited up. 2. The lumbricoides is about the same length with the lumbricus terrestris, or common earth-worm; but it wants the protuberant ring towards the middle of the body, the only mark by which they can properly be distinguished. The body of the lumbricoides is cylindrical, and tubulated at each extremity; but the tail is somewhat triangular. The lumbricoides is the worm which is most commonly found in the human intestines. It is viviparous, and produces vast numbers. For the method of expelling these two kinds of insects, see the Index subjoined to Medicine.