Source : Webster's Revised Unabridged Dictionary (1913)

Trachystomata \Tra`chy*stom"a*ta\, n. pl. [NL., fr. Gr. ? rough
   + stoma.] (Zo["o]l.)
   An order of tailed aquatic amphibians, including {Siren} and
   {Pseudobranchus}. They have anterior legs only, are eel-like
   in form, and have no teeth except a small patch on the
   palate. The external gills are persistent through life.