Amphisbaena, a mythic serpent of Libya, fabled to have two heads, and to be able to move backwards or forwards with equal facility. The idea lingered on till recent times, and Tennyson aptly embodies the popular notion of this fabulous animal when he speaks of
"Two vipers of one breed - an amphisbaena,
Each end a sting."
The name is now applied to a genus of limbless lizards, with thirteen species, from Spain, Northern Africa, Asia Minor, South America, and the West Indies. They are from 18 to 24 inches long, and of nearly uniform thickness; the head is small, and there is scarcely any perceptible tail. They burrow in soft earth, and live on insects and worms.