Source : Webster's Revised Unabridged Dictionary (1913)

Siredon \Si*re"don\, n. [NL., from Gr. ??? a siren.] (Zo["o]l.)
   The larval form of any salamander while it still has external
   gills; especially, one of those which, like the axolotl
   ({Amblystoma Mexicanum}), sometimes lay eggs while in this
   larval state, but which under more favorable conditions lose
   their gills and become normal salamanders. See also
   {Axolotl}.