which have again taken to the water and are tongueless, have lost this organ. As I have shown elsewhere,[72] the epichordal development of the vertebrae is likewise a secondary feature, far from primitive; and the tendency of the shortening of the vertebral column, which has reached its extreme in _Hymenochirus_, points to the same conclusion. The apparatus of the shoulder-girdle and sternum is in the last transitional stage from the former arciferous to the typically consolidated firmisternal {146}type. In fact there is little left which is primitive, but much that is very specialised and highly developed in the Aglossa, mostly in adaptation to their absolutely aquatic life, to which they must however have taken very early. They are in a position somewhat analogous to the Ratitae among Birds, which are likewise an old group, although many of their most striking features have been acquired secondarily. _Xenopus_ s. _Dactylethra_. The upper jaw is furnished with teeth. The ilia are attached to the ninth vertebra. The pupil is round. The terminal phalanges are pointed. The fingers are free, the toes broadly webbed, and the first three are covered with sharply pointed, horny, black-brown nails, a feature which is alluded to by the alternative generic names. A cutaneous tentacle projects from below the eye and naturally invites comparison with the tentacle of the Apoda and of Urodela. The skin is smooth, rich in mucous glands, besides certain tube-like apparatuses, possibly sensory, which are scattered over the body, especially on the head, and form a conspicuous series of white dots along the dorso-lateral line, from the eye to the vent. The general colour of the upper parts is olive brown, mottled darker, while the under parts are whitish. The female has three cutaneous flaps closing the vent. The male develops black nuptial brushes along the inner side of the fingers. There are several species, all African (Ethiopian). _X. laevis_, ranging from the Cape to Abyssinia, is distinguished by the absence of a metatarsal spur. The tentacle is very short. Size about 3 inches. _X. muelleri_ of Zanzibar and Benguella, is smaller. The tentacle is conspicuous, as long as the diameter of the eye. The inner metatarsal tubercle carries a sharp claw. _X. calcaratus_ of tropical West Africa is only 2 inches long, and has strong metatarsal claws, short tentacles and very minute eyes.