\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.