The myriapods (class Myriapoda) are those unpleasant creatures more commonly known as centipedes, millipedes, or thousand-legged worms. They have a wormlike form, with the body divided into segments, a distinct head with antennæ, jaws and several single eyes, and a varying number of air tubes, or tracheæ; two sexes exist, and eggs are laid in the ground within cases formed by the mother of pellets of mud. They vary in size from an almost invisible minuteness to a length in some tropical species of six or more inches. The centipedes (Chilopoda) are those flattened forms so often seen in and about rotting wood and vegetation or in moist ground, their bodies looking like a chain of plates joined together by flexible skin, each section having a single pair of legs, usually very short, but in one sort (Cermatia) each leg is longer than the body, and the hinder pair twice as long, matched by two very long feelers. Most of them are predacious, feeding on anything they can catch, and their strong jaws exude poison. The larger ones may inflict a very painful bite if incautiously handled.

(Scolopendra gigas )

Another group, the Diploda, are known as galley worms, or millipedes, and have two pairs of bristlelike legs on each segment. Here the body is as round as that of an earthworm, and is incased in ahard, chitinous shell, usually red-brown in color; and when disturbed they coil up and emit an acrid, unpleasant odor as a defense.