Any long, slender amphibian of the genus Siren or family
   Sirenidae, destitute of hind legs and pelvis, and having permanent
   external gills as well as lungs. They inhabit the swamps, lagoons, and
   ditches of the Southern United States. The more common species (Siren
   lacertina) is dull lead-gray in color, and becames two feet long.