a name commonly given to a lizard found in the sandy deserts of New Mexico, Arizona and Texas. It is a repulsive animal, usually about a foot in length and often larger, with a fat tail and short, weak legs. Its scales are brilliant orange and jet black. It is closely allied to the heloderm, and, like the Mexican species, it is poisonous. It has grooved teeth and highly developed salivary glands at their bases. The bite of the gila monster is rapidly fatal to small mammals and birds and very injurious, though seldom fatal, to man. The heloderms are the only lizards known to be venomous.