The colour of the iguana changes, like that of the chameleon. The Brazilians, indeed, call it the chameleon. Its food consists almost entirely of fruits and other vegetable substances, though some species are supposed to be omnivorous. The natives frequently tame it, when it willingly allows itself to be carried about by its owner, though it at once distinguishes strangers. There are, however, numerous species of iguanas; indeed, the family contains fifty genera--the true iguanas being all inhabitants of the New World. To its predecessor, which it closely resembles in bony structure, the largest is but a mere pigmy--for that extinct monster must have been about seventy feet in length, the length of the tail alone being fifty-two feet, and the circumference of the body fourteen and a half feet; while its thigh-bone was twenty times the size of that of the modern iguana. Vast as was the inhabitant of the ancient world, it was herbivorous, like that of the comparatively Lilliputian creature of the present day. Everywhere the agile, beautifully-tinted lizards abound, sunning themselves on logs of wood, or scampering over the sandy soil. Now they may be seen turning round the trunk of a tree, much as a squirrel does, watching the passer-by, and trying to keep out of sight. Some are of a dark coppery colour, others have backs of the most brilliant silky green and blue, while others are marked with delicate shades of yellow and brown. The largest of their family is the teguexin, or variegated lizard. Sometimes it is called the safeguard, from the idea--probably an idle fable--that, like the monitors of the Nile, they give notice of the approach of the alligator by their loud hissing. There are several species which inhabit the hot, sandy plains, or dense, damp underwood near the rivers and lakes. One of them exceeds five feet in length, and is extremely active. It feeds almost entirely on snakes, frogs, and toads, but occasionally devours poultry, and breakfasts off their eggs. It is also somewhat of a cannibal, for though it will not eat its own species, it does occasionally those of a somewhat smaller lizard allied to it. It possesses strong teeth, and can bite with great force; indeed, when attacked it defends itself fiercely, and when seizing a foe can seldom be compelled to let go. Its colour is variable, but generally the upper parts of the body are deep black, with mottlings of yellow or green; while on the higher portions of its sides are a series of white spots, the under part being chiefly yellow, with black bands. The little ameiva, on which it occasionally preys, is of a dark olive colour, speckled with black about the neck.