CHAMELEON, the common name of members of one of the sub-orders of lizards ; the same name is used also for the American lizards of the genus Anolis (Igu anidae). The great majority of the species of this sub-order are referable to the genus Chamae leon (containing about 7o spe cies), the remaining two genera, Rhampholeon and Brookesia, con taining only a few dwarfed forms. The geographical range of the group is the whole of Africa and Madagascar, Arabia, southern In dia and Ceylon, but it is in the forests of central Africa and Madagascar that most diversified forms occur. The grasping feet are formed by the fusion of the digits into two opposable bundles, the two outer digits being op posed to the three inner on the fore-limb and vice versa on the hind-limb, and, like the prehensile tail, are correlated with the ar boreal habits of these animals. The eyes are large and independently movable, but the eyelids are fused into one circular fold which leaves only the pupil visible; the eyes can also, unlike those of other reptiles, be focussed upon one spot, giving the binocular vision necessary for the nice appreciation of distances required in the use of the tongue. This organ is very large, club-shaped and provided with a sticky secretion at its tip; the basal portion is narrow and composed of very elastic fibres, which, when the tongue is not in use, are telescoped over the elongated copular piece of the hyoid which acts as a support. By filling the apparatus with blood and by the action of certain muscles the tongue can be shot out to a remarkable distance, seven or eight inches in a full grown specimen of the common north African species (C. Chamae leon); the elasticity of the basal fibres assists in its rapid with drawal. It is by means of this extraordinary mechanism that the chameleon secures its prey; flies and other insects are deliberately stalked until within range, then out shoots the tongue and the victim is withdrawn adhering to its sticky tip.
The ability of chameleons to change colour has made their name almost proverbial, but their powers are usually exaggerated and are quite equalled by those of some other lizards. Change of colour is partly reflex and partly controlled by the will; changes in the intensity of light, change of temperature and emotion pro duce marked and characteristic changes, but there is little direct response to the colour of the environment. The normal colour of the common chameleon may be grey-green with innumerable small dark specks and with rows of pale brown patches on the sides of the body; in the dark at normal temperatures the colour fades to a cream-colour with irregular yellow spots but exposure to hot sunlight causes the whole animal to darken until it may be uni formly dull black. High temperatures without direct sunlight usually produce greens and low temperatures dull greys ; excite ment and fright bring paler shades with brown patches and yellow spots whilst anger causes the lighter areas to darken. Blue and red do not seem to be within the range of this particular species but the combinations of green, yellow, brown, black and white and their various shades are almost endless.
Propagation is in most cases by means of eggs; these are small, oval, white in colour and provided with a tough parchment-like shell. They are buried by the mother and left to be incubated by the heat of the sun. A few species, e.g., the dwarf chameleon of South Africa (C. pumilus), retain the eggs within the body until they hatch, so that the young are born alive.
An extraordinary feature of the group is a tendency towards the production of excrescences on the head. Many species have the occiput produced backwards into a pointed casque and this may assume extraordinary dimensions; but the most remarkable devel opments are the horns of some of the tropical African and Malagasy species. In different forms there may be one, two or three horns or a single, flexible, dermal flap on the tip of the snout ; in some species these appendages occur only on the male but in others they are present on both sexes. (D. M. S. WV.)