horned lizard or horned toad, broad, flat-bodied lizards of the genus Phrynosoma, found in arid regions from extreme SW Canada to Guatemala. There are several species in the United States W of the Mississippi. The body is 3 to 5 in. (7.6 to 12.7 cm) long; it has a short, thin tail, a short neck, and short legs. There are spines on the head, sides, and back. Horned lizards are protectively colored, usually in dull grays and browns. They feed on insects, especially ants, and are often found buried in the sand, with only their heads exposed. In some species the female lays eggs; in others the eggs are incubated internally and the young are born alive. When alarmed, members of some species eject a thin stream of blood from the nictitating membrane of the eye for a distance of several feet. Horned lizards are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Squamata, family Iguanidae.