Helodermatidae (beaded lizards, venomous lizards; order Squamata, suborder Sauria) A family that comprises the only poisonous lizards. The venom glands are at the rear of the lower jaw (unlike those of snakes). The body is cylindrical, with powerful limbs, and a thick, rounded tail. The upper surface is covered with large, bony scales. Heloderma suspectum (gila monster) is a sluggish, nocturnal lizard, mainly pink and brown with black shading, up to 60 cm long, that burrows in sand and preys principally on small rodents; its bite is seldom fatal to humans. There are two species in the family, occurring from Nevada to Mexico.

beaded lizard See HELODERMATIDAE.