from the GNU version of the Collaborative International Dictionary of English
- n.pl. A grand division of the Vertebrata, including the Amphibia and Fishes.
from The Century Dictionary and Cyclopedia
- 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.
Sorry, no etymologies found.
It now appears that they form with the latter one great group -- the ichthyopsida of