Proteus, a genus of tailed amphibians with persistent gills, represented by two or three species in the caves of Carniola and Dalmatia. They are lank animals, towards a foot in length; and with their peculiar habitat may be associated the pale colour of the flesh, and the embryonic state of the eyes, which are hidden beneath the surface. It has been shown, however, that sensitiveness to diffuse light persists. A nearly related genus, Necturus, lives in North American rivers and lakes. The name Protens animalcule was formerly used as a synonym for Amœba (q.v.).