Amphibia

Amphibia Am*phib"i*a, n. pl. [See {Amphibium}.] (Zo["o]l.) One of the classes of vertebrates. [1913 Webster]

Note: The Amphibia are distinguished by having usually no scales, by having eggs and embryos similar to those of fishes, and by undergoing a complete metamorphosis, the young having gills. There are three living orders: (1) The tailless, as the frogs ({Anura}); (2) The tailed ({Urodela}), as the salamanders, and the siren group ({Sirenoidea}), which retain the gills of the young state (hence called {Perennibranchiata}) through the adult state, among which are the siren, proteus, etc.; (3) The C[oe]cilians, or serpentlike Amphibia ({Ophiomorpha} or {Gymnophiona}), with minute scales and without limbs. The extinct Labyrinthodonts also belonged to this class. The term is sometimes loosely applied to both reptiles and amphibians collectively. [1913 Webster]