Centipede, an .articulated animal, formerly considered an insect, but since the time of Dr. Leach placed in the class myriapoda, and in the genus scolojiendra. This class is distinguished from insects by the far greater number of feet, by the more numerous segments of the body, and by the absence of any distinct division between the thorax and abdomen. With the exception of the first, each segment has a pair of legs, terminated generally by a single hook; from the occurrence of the stigmata, or respiratory openings, on each alternate segment, La-treille and others, from the analogy of insects proper (which have two stigmata on each segment), have considered these as semi-segments, and have consequently given two pairs of legs to each segment. The feet are much approximated to each other for the whole length of the body; the mandibles are bi-articulated, and followed by a piece formed like a labium with articulated feet-like divisions, corresponding in position to the languette of Crustacea; then come two pairs of little feet, of which the second, hook-shaped often, seem to replace the four jaws of crustaceans, or the two maxillae and lower lip of insects; they may be regarded as maxillary feet. The antenna) are two, varying greatly in their shape, length, and number of joints.
The organs of vision are usually formed by the union of simple eyes, but in some they resemble the compound eyes of insects, with larger facets. All myriapods are wingless. Unlike insects, in this class the number of the rings, and of the feet belonging to them, increases with their age; from the fact that some genera are born without feet, Latreille asserts that they undergo a true metamorphosis, though the separate states of larva, pupa, and imago do not exist in them anymore than they do in most apterous insects. The organs of respiration consist of two principal parallel tracheal along the body, into which the stigmata open. The myriapods seem to approximate somewhat to the Crustacea on one hand, and to the insects on the other. They generally avoid the light, concealing themselves under stones, beneath the bark of trees, in old timber, and similar localities; some live in fruits, others destroy vegetables, and many feed on dead and living animal substances. Latreille divides myriapoda into two orders: 1, chilognatha, of which the best known genus is iulus (Latr.); and 2, chilopoda, containing the genus scolopendra, which, in the unrestricted latitude given it by Liniueus, included all the genera of the order, all of which have at various times been designated as centipedes or millepedes.
In the order cliilopoda the antennno are slender toward the extremity, having 14 or more joints; the mouth consists of two mandibles with a pal-piform appendage, terminated like the bowl of a spoon with indented edges; the labium is quad-rifid, and its two lateral divisions, the largest, are transversely ringed, and resemble the membranous feet of caterpillars; they have besides two palpi or little feet, united at the base and unguiculated at the end, and a second labium formed by a second pair of feet, terminated by a strong movable hook pierced at the end for the issue of an acrid liquid.
The body is membranous and flattened, each ring being covered by a coriaceous plate, and having for the most part but one pair of feet, the terminal segment being elongated into a kind of tail; the sexual organs are interior, and placed at the posterior extremity of the body. - The centipedes move very rapidly in an undulating manner; they can walk backward, using only the four hind legs, which in ordinary progression are dragged after them. They are carnivorous, and are much dreaded by the inhabitants of warm climates, where they attain a large size, and are capable of inflicting dangerous wounds; it is said that their bite, though more painful than that of the scorpion, is never fatal; the common species of Europe (litliobius forjieatus, Linn.), very abundant under stones in the summer season, is quite harmless, though repulsive in its aspect. The genus scutigera (Lam.) has the body covered with 8 plates, 15 pairs of legs, and large reticulated eyes; they are nocturnal in their habits, and pierce their insect prey with their mouth-hooks, producing almost instant death; according to Illiger, they are dreaded by the inhabitants of Hungary. The genus scolopendra (Leach) has 21 pairs of legs, of which the basal joints of the terminal legs are armed with spines; the segments are nearly of equal size and number above and below.
The S. cingu-lata (Latr.) of southern Europe is almost as large as some of the species of tropical America. Several species of South America and the West Indies have doubtless been confounded under the S. morsitans (Linn.), one of which grows to the length of a foot; very large species also occur in Asia, Africa, and the Indian archipelago. Ammonia is the best application to their lutes. Of the genus crytops, Dr. Leach mentions two species found in the vicinity of London; the eyes are very small, the antenna) are grained, and the basal joint of the more slender hind feet is without spines, in the genus geophilus (Leach), the antennas have only 14 joints, but the leas vary in number from 42 to nearly 300; they are very slender, and some are phosphorescent; they are destructive to fruit and vegetables. - The position of the myriapoda can hardly be said to be determined. Siebold says they do not properly belong either to arachnida or insecta, and he classes them under Crustacea. Rymer Jones observes that they differ from Crustacea by their respiring air by means of trachea?, and from annelids by their jointed legs, and that they seem to be an osculant group, allied to annelids, insects, arachnida, and Crustacea; they have urinary organs like insects, which Crustacea have not.
Prof. Agassiz makes them the lowest order of the class of insects, the other orders being arachnids and insects •proper. Newport traces the nervous system from the highest chilognatha, the most perfect of which are connected on the one hand with Crustacea and on the other with true insects, through the geopliili (the lowest vermiform type of the chilopoda), to the tailed arachnida (the scorpion), and through scolopendra, litlio-bius, and scutigera, the last of which connects the myriapoda on the one hand with true insects, and on the other with arachnida. The heart or dorsal vessel, as in insects and arachnida, is divided into several compartments, corresponding in number to the abdominal segments.