Monitor, a name given to a genus of Lizards somewhat isolated from other lizards in structural characters; in some respects they approach the Crocodylia, which are the highest of existing reptiles. They are the largest of existing lizards; a specimen acquired by the College of Surgeons in London measured 6 feet 10 inches. The tail of the greater number is laterally compressed, the better to adapt them to aquatic habits. They have received the name Monitor from a notion that they give warning by a hissing sound of the approach of a crocodile or alligator. There is only one genus, with many species.—The Monitor or Varan of the Nile
(Varanus niloticus) is of a rather slender form, and has a long tail. It is olive-gray, mottled with black. It attains a length of five or six feet. Crocodiles' eggs or young crocodiles form the chief part of its food. It is a curious superstition in India, that the young of the monitor is more deadly than the most venomous serpent.