MYRIAPODA, a group formerly classified among the arthropodan animals, hut now bet ter known. It includes the groups of Chilo poda, or centipedes, and the Diplopoda, mille peds or galley-worms. The features common to all are the elongate worm-like body consist ing of a head and behind this the trunk of numerous similar leg-bearing segments, not di vided into thorax and abdomen. They are all habitants of dark and obscure places,— under logs and stones and the bark of trees. All but two species are terrestrial; those two are semi aquatic, living between the high and low-water levels on the sea-coast. Closer analysis shows that the chilopods are related to the crustacea while the diplopods are allied to the worms. In the chilopods the head bears a pair of groups of simple eyes, a pair of antenna and three pairs of jaws (mandibles, maxilla, labium), while the first pair of trunk appendages be comes connected with the head and serve as poison-jaws. The trunk-segments are all sim ilar, and each bears one pair of legs, the num. her of segments ranging from 15 to 170 or more. The body-segments are flattened and the reproductive openings are at the hinder end of the body. Most of the chilopoda are carnivoro ous and ferocious and are very quick in move ment. The most noticeable members of the group are the centipedes (Scolopendridce) of the tropics, some of which are nearly a foot in length and have considerable poison powers.
See CENTIPEDES.
In the diplopoda the head bears but two pairs of jaws (mandibles and lower lip or gnath ochilarium), while the trunk-segments are usu ally circular in section, and each, except a few near the head, bears two pairs of legs, an ex ception to the otherwise universal rule among arthropods of a pair of legs to a somite. The range of segments is even greater than in the chilopods, there being nine in Pauropoda and 200 in some Polycoludce. The reproductive organs lie ventral to the intestine, and the ex ternal openings are a little behind the head. The Diptopoda live mostly upon decaying vege tation and are extremely slow in movement. For protection they rely upon the very thick and hard walls of the bodies, and in some species upon peculiar stink glands which open on the sides of the body. See MILLEPED.
Fossil Myriapods appear in the Devonian rocks and they are found in all parts of the world to-day. Most of the American species are described in Bollman's of America' (United States National Museum, 1893). •