412 MANUAL OF ZOOLOGY. 



The Iguanida constitute another large family of Lizards, 

 also belonging partly to the Old and partly to the New World. 

 They are often divided into " ground-iguanas," in which the 



Fig. 161. Head of a Chameleon (C. Petersii) after Gray. 



body is flat and depressed, and "tree-iguanas," in which the 

 body is compressed. The members of the genus Iguana itself 

 (fig. 159) are confined to the New World, and are distinguished 

 by having the throat furnished with a pendulous dewlap or 

 fold of skin, the edge of which is toothed. The back and 

 tail, too, are furnished with an erect crest of pointed scales. 

 The Iguana attains a length of from four to five feet, and 

 though not of a very inviting appearance, is highly esteemed 

 as food. More remarkable than the true Iguanas is the little 

 Flying Dragon (Draco volans) of the East Indies and Indian 

 Archipelago. In this singular little Lizard there is a broad 

 membranous expansion on each side, formed by a fold of the 

 integument, supported upon the anterior false ribs, which run 

 straight out from the spinal column. By means of these 

 lateral expansions of the skin, the Draco volans can take long 

 flying leaps from tree to tree, and can pursue the insects on 

 which it feeds ; but the lateral membranes simply act as 

 parachutes, and there is no power of true flight, properly so 

 called. 



The last family of the living Lizards which requires notice 

 is that of the Chamceleontidcz, containing the familiar little 

 Chamceleo Africanus, which occurs abundantly in the north of 

 Africa and in Egypt, and is so well known for its power of 

 changing its colour under irritation or excitement. In this 

 genus the eye (fig. 161) is of large size, and is covered by a 

 single circular lid, formed by a coalescence of the two lids, 

 and perforated centrally by a small aperture, by which the 

 rays of light reach the pupil. The Chameleon is naturally a 



