466 MANUAL OF ZOOLOGY. 



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 Chamaleontida, containing the familiar little 

 Chamtzleo Africamis, 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. 202) 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 sluggish 



Fig. 202. Head of a Chameleon (C. Petersii) after Gray. 



animal, but it catches its food, consisting of insects, by darting 

 out its long, fleshy, and glutinous tongue an operation which 

 it effects with the most extraordinary rapidity. 



The tail in the Chameleons is round and prehensile, the body 

 compressed, and the skin like shagreen. The toes are adapted 

 for the arboreal life and scansorial habits of the animal, being 

 so arranged as to form two equal and opposable sets. The 

 lungs are excessively voluminous. The Chameleons are 

 exceedingly sluggish and slow in their movements, and are 

 confined to the warmer parts of the Old World. 



DISTRIBUTION OF LACERTILIA IN TIME. It is hardly pos- 

 sible, with our present knowledge, to speak very positively as 

 to the exact range of the Lacertilia in time. This uncertainty 

 arises from two causes firstly, that there is some doubt as to 

 the exact age of some deposits which have yielded Lacertilian 

 remains ; and, secondly, that the affinities of some extinct 



