Source : Webster's Revised Unabridged Dictionary (1913)

Labyrinthodonta \Lab`y*rin`tho*don"ta\, n. pl. [NL. See
   {Labyrinthodon}.] (Paleon.)
   An extinct order of Amphibia, including the typical genus
   Labyrinthodon, and many other allied forms, from the
   Carboniferous, Permian, and Triassic formations. By recent
   writers they are divided into two or more orders. See
   {Stegocephala}.

Stegocephala \Steg`o*ceph"a*la\, n. pl. [NL., fr. Gr. ? roof + ?
   head.] (Paleon.)
   An extinct order of amphibians found fossil in the Mesozoic
   rocks; called also {Stegocephali}, and {Labyrinthodonta}.

   Note: Their teeth, in transverse sections, usually show a
         labyrinthiform arrangement of the cement and dentine.
         The under side of the body was covered with bony
         plates. Some of the Stegocephala were of very large
         size, and the form of the body varied from short, stout
         forms to others that were as slender as serpents.

Source : WordNet®

Labyrinthodonta
     n : extinct amphibians typically resembling heavy-bodied
         salamanders or crocodiles and having a solid flattened
         skull and conical teeth; Devonian through Triassic [syn:
         {Labyrinthodontia}, {superorder Labyrinthodontia}, {superorder
         Labyrinthodonta}]