Myriapoda
An order of Articulata, or jointed animals, greatly resembling insects in being made up of horny rings (chitine), held together by soft membranes between them, as well as in breathing by air tubes (tracheae) branching all through the body and opening on its surface by little mouths (spiracles), across each of which lies a structure like a sieve, that prevents the entrance of dust with the air. These animals also agree with insects in the general structure of the internal organs; in having a distinct head with one pair of antennae or feelers, and simple eyes, usually in a group on each side, and legs made up of several distinct joints. They differ from insects in having no well-defined thorax, in the rings of the body being very numerous, and in their numerous pairs of legs, whence the popular names of Centipede and Millipede. The eggs are laid in the localities frequented by the animals, such as below stones, dead leaves, &c. The young ones, on emerging from the eggs, have only three pairs of true legs; but, at each change of skin during their growth, the number of the legs increase, as does also the number of simple eyes. Hence, till maturity is reached, the numbers of legs and eyes are too variable with age to permit of laying much stress upon them in determining species. Myriapoda usually feed upon insects, or upon plants; most frequently they feed upon decaying parts of plants, but a few also attack living cultivated plants, and injure them considerably. They belong chiefly to two great groups, the Centipedes (Chilopoda) and the Millipedes (Chilognatha), and may be readily distinguished from one another by the following characters. Centipedes have, for the most part, flattened depressed bodies, with only one pair of legs on each ring of the body. The lower surface of each ring is formed by a flat plate, which keeps the legs apart, so that they are seen projecting beyond the sides of the rings when the animals are crawling. The last pair of legs is longer and stronger than the others, and projects back-wards. The front pair is modified to form two tapering, sharp-pointed, jaw-like oranges, which can be made to pierce the skin of the animals that serve as food. Each of these organs is traversed by a tube that conveys poison from a gland near the head into the wound in the bodies of the prey, or those of assailants if being used in self-defence. Our native species are all of small size (1/2in. to 3in. long, and quite slender), but many tropical species are from 6in. to 12in. long, and give a very painful or even dangerous bite. Centipedes mostly feed on insects, or on others of the lower animals; hence, they are beneficial to gardeners. They are often met with in digging gardens. One kind (Scolopendra electricus, or Geophilus longicornis), sparingly met with in England, has the power of emitting a feeble light at times. The Millipedes (Chilognatha) are easily recognised by their legs being more numerous than those of Centipedes, each of the rings behind the three that immediately follow the head seeming to bear two pairs. The legs are also inserted close to the middle line below, and are too short to project beyond the sides of the body when the animal is walking. The body is usually nearly cylindrical, less often depressed. This group possess no poison fangs. For further particulars regarding these animals and their relation to horticulture, see Millipedes.