CHAMELEON, ka-mel'yun or ka-me'le-on, lizard belonging to the family Chamceleontida% The chameleons are generally considered as constituting a sub-order or equivalent primary division of the Lacertilia (q.v.). All parts of their anatomy present striking peculiarities. The parietal and squamosal bones of the skull form a bony tripod which supports the conspicuous crest or calque on the posterior part of the head. In many species the strangeness of the physiognomy is enhanced by warts, serrated crests and prominent spines. Trifid teeth are situated on the ridge (acrodont) of the maxil lary and dentary bones, but the premaxillary is toothless. The eyelids are almost completely united, leaving only a minute circular orifice through which the animal sees, and which moves with the eyeball in its almost constant royings. More remarkable still the two eyeballs move quite independently; one may be directed at an object behind while the other views one in front. The tongue is club-shaped at the free end and slips into a sheath at the base, from which it can be projected to a distance of more than half the total length of the animal, and return, like a bit of rubber, with great rapidity to its former position. Unique among lizards is the prehensile tail, which rolls downward in a flat spiral and is utilized for clinging to twigs. Serving the same purpose in the arboreal life of the animal are the almost equally peculiar feet, which have five toes arranged in two op posed sets on both fore and hind feet. The lungs are into a series of long tubular di verticula, which extend to all parts of the trunk, so that the chameleon is enabled to,swell up its body in the fashion of a toad when angry or threatened. These animals subsist entirely on insects caught by the protrusile, somewhat sticky tongue; and are reproduced by eggs laid in the ground.
But the chameleon is most famous for a faculty by no means confined to it, but common to many lizards and other animals — the well known facility with which it changes its colors. This is accomplished at the will of the animal, or results from the direct influence of external stimuli, by a relatively simple mechanism. The outer portion of the skin or epidermis is trans parent; beneath this is a layer of cells filled with granules and oil-drops that appear white or yellow ; among and beneath these are large Irregular chromatophores, or cells filled with black and red pigment granules. These chro matophores are under the control of the nervous system, and have the power, when appropriately stimulated, of sending out long branching proc esses filled with pigment into the spaces be tween and external to the light-colored cells.
When this occurs the latter cells are concealed by a pigment curtain and the animal appears dark-colored; when, on the other hand, the chromatophore processes are withdrawn, and the pigment is concentrated in the deeper layers of the skin, the animal appears pale. The rapid play of colors is due to the interchange of these two conditions in varying degrees.
More than 50 species of chameleons are known, belonging to the typical genus Chame leon, and a few others. With the exception of a few species which inhabit Arabia and India, and one whose range extends across the Med iterranean into southern Spain, all are con fined to Africa, and a large number of the strangest forms to the island of Madagascar. The common chameleon (C. vulgaris) inhabits the shores of the Mediterranean and Asia Minor, and through being so well known to Europeans, has made the peculiarities of these lizards almost proverbial.
In the United States the name chameleon is commonly applied to a lizard (Anolis caro linensis) and its allies, belonging to a quite different group, a genus of the family Iguanide. Like its African namesake it changes its colors with great facility. (Consult Proceedings Amer. Acad. Arts and Sciences, XL, 10, 1904). It may be bright green, yellowish-gray, rich brown, or almost black, and the male is peculiar in having beneath the throat a pouch of elastic skin which can be inflated by means of a pair of delicate bony rods belonging to the skeleton of the tongue, when it appears of a flaming orange or vermilion color. They are dainty, smooth bodied little animals, and are chiefly arboreal, jumping from twig to twig in pursuit of in sects with an activity that contrasts strongly with the sluggishness of the European chame leon, which depends upon its projectile tongue to secure its game. Anohs carolinensis is the only member of the genus which enters the United States, and is quite common in Florida and other southern States, from which many were shipped to the North a few years ago to supply the requirements of a silly fashion in vogue at that time of wearing one of these pretty lizards secured to the dress by a tiny golden chain about its neck. Owing to the ignorance of the wearers, many of the chame leons quickly succumbed to thirst, as they, in common with most lizards, require a constant supply of water. Consult Gadow, ; and (New York 1911) Ditmars, The Reptile Book) (New York 1907) • Pycraft, (Story of Reptile Life> (London 1905).