A class, or subclass, of arthropods, related to the hexapod insects, from which they differ in having the body made up of numerous similar segments, nearly all of which bear true jointed legs. They have one pair of antennæ, three pairs of mouth organs, and numerous tracheæ, similar to those of true insects. The larvæ, when first hatched, often have but three pairs of legs. See Centiped, Galleyworm, Milliped.

arthropods having the body composed of numerous double somites each with two pairs of legs: millipedes

Myriapoda is a subphylum of arthropods containing millipedes, centipedes and others. The group contains 13,000 species, all of which are terrestrial . Although their name suggests they have myriad (10,000) legs, myriapods range from having over 750 legs (Illacme plenipes)  to having fewer than ten legs.