\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}.