The only living animal phylum with true lobopods (annulate, saclike legs with internal musculature). There are about 70 known living species in two families, Peripatopsidae and Peripatidae. These terrestrial animals are frequently referred to as Peripatus. Onychophora comprise a single class or order of the same name. They were once considered a missing link between annelid worms and arthropods, but are best considered to be aligned with the arthropods.