Amphibia \Am*phib"i*a\, n. pl. [See Amphibium.]
(Zo["o]l.)
One of the classes of vertebrates.
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.
Source: Webster's Revised Unabridged Dictionary (1913)
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