According to my "AA Book of the British Countryside" there are three separate answers. Centipedes are distantly related to ants, and spiders. The best known of the British species is Lithobius Forficatus. The name centipede literally means 'a hundred legs' but the number of legs varies from species to species, ranging from 17 to 177 pairs. Each of the many segments of their bodies bears a pair of legs..........Although there are at least 44 species of Millipedes in Britain, many are rare. They differ from centipedes in having two pairs of legs - rather than one pair- on most of their body segments, giving a total of about 150 legs in the largest British specie. Common species in the British Isles are Glomeris Marginata, found in woodlands, Oxidus Gracilis, which lives in greenhouses, Blaniulus Guttulatus, living in arable soil, PlyxenusLagurus, found under stones and bark and lastly Polydesmus Augustus, the common field flat-back species. Woodlouse is the only land-living relative of the aquatic crabs, shrimps and lobsters. The common pill-bug is Armadillidium Vulgare and the Common Woodlouse is Oniscus Asellus.