from The Century Dictionary.
- One of three primary groups or provinces of vertebrates in Huxley's classification (the other two being Sauropsida and Mammalia), comprising the amphibians or batrachians and the fish and fish-like vertebrates; the branchiate or anamniotic Vertebrata.
from the GNU version of the Collaborative International Dictionary of English.
- noun plural (Zoöl.) A grand division of the Vertebrata, including the Amphibia and Fishes.
Sorry, no etymologies found.
It now appears that they form with the latter one great group -- the ichthyopsida of