Peripatus is the genus which is the only member of the remarkable class known as the Protracheata or Onychophora. It is certainly one of the most interesting and abnormal animals in the whole range of the Invertebrates. It has a soft worm-like body, with a series of rudely jointed limbs placed at equal distances along the body. The antennae consist of a single pair; they are blunt and composed of a series of ring-like segments. The first two pairs of limbs are modified to help in feeding; the first pair acts as the jaws and are enclosed in a mouth cavity, while the second pair is represented by two papillae, at the ends of which the slime glands discharge mucus. Breathing is effected by a series of internal respiratory tubes which ramify through the body. The functional body cavity is a "pseudocoele" [Coelome], while the true body cavity or coelome is represented only by a number of small vesicles in the bases of the legs. The interest of the genus -- apart from some questions of the nature of the body cavity and the course of development -- is that, while it is worm-like in appearance and in the character of its nephridia or kidneys, it is more closely allied to the Myriapoda, There are numerous species which are very widely scattered, and occur in the West Indies, South and Central America, the Cape of Good Hope, Australia, and New Zealand. The animals live under leaves and stones or in decayed.wood.