in zoology, a genus of serpents belonging to the order of amphibia serpentes, so called from the false notion of its having two heads, because it moves with either end foremost.

The head of the amphisbena is small, smooth, and blunt; the nostrils are very small; the eyes are minute and blackish; and the mouth is furnished with a great number of small teeth. The body is cylindrical, about a foot long, and divided into about 200 annular convex segments like those of a worm; and it has about 40 longitudinal streaks, of which 12 on each side are in the form of small croissants like the Roman X; the anus is a transverse slit; and the last ring or segment of the belly has eight small papillae, forming a transverse line before the anus; the tail, i.e., all the space below the anus, is short, consisting of thirty annular segments, without being marked with the cross-lines, and is thick and blunt at the point. The colour of the whole animal is black, variegated with white; but the black prevails most on the back, and the white on the belly. It has a great resemblance to a worm, living in the earth, and moving equally well with either end foremost. There are but two species, viz. 1. The fuliginosa, which answers exactly to the above description, and is found in Libya, and in different parts of America. 2. The alba, which is totally white, is a native of both the Indies, and is generally found in ant-hills. The bite of the amphisbena is reckoned to be mortal by many authors; but as it is not furnished with dog-fangs, the usual instruments of conveying the poison of serpents, later writers esteem it not to be poisonous. They feed upon ants and earth-worms, but particularly the latter. See plate XI. fig. 2.