DIVISION II. NEMATELMLA (q.v.). Scoleeida. having an elongated and cylindrical body. Most of the division have an annulated integument, but there is no true segmen tation, and rarely locomotive appendages. They are mostly unisexual, and are para sitic during the whole or a part of their existence. The division comprises three orders: Order I. Acanthorephala, thorn-headed worms (Gr. aleantho, thorn; kephale, head). These animals are entirely parasitic, vermiform, and have no month or alimentary canal. They have a proboscis armed with curved hooks. At the base of the proboscis there is a single ganglion of nerve matter giving off radiating filaments in all directions. It has been discovered that, as in the tnaida, the adult worm is developed within a hooked embryo. These thorn-headed acorns are among the most formidable that infest the intestinal canal of vertebrates, particularly of birds and fishes.
Order II. Gordiacea, hair-worms. See NEMATELMIA. These are thread-like, pa•a sitic organisms, which in their earlier stages inhabit the bodies of insects, such as bee les and grasshoppers. They have a mouth and alimentary canal. Vile sexes are quit their hosts in order to breed. They resemble hairs, and are often manv times as long as the insects they infest. See WORMS.
order III. iVernatoda or Nematoidea (q.v.). Most of these animals are internal para. sites, inhabiting the intestinal canal, pulmonary tubes, or cellular tissues of man and other animals; but many are not parasitic. The best known are the osearis lumbricoides, the round worm of the stomach and intestines (see AscAtus); the alweris termiClaari8, Or (q.v.); fliaria medincnsis. or Guinea-worm (q.v.); trichina spiralis vinegar eel. See SCLEROSTOMA and HEMATOZOA.