272 



VERTEBRATE ANIMALS. 



various diseases. A nearly allied species is tlie bluo-tailed Lizard 

 (Sctncus faxciat us) of the United States. 



The Geckos {O erlcoiidce) form a large group of night-loving Lizards, 

 •which are found iu most parts of the woi'ld, and chiefly deserve 

 notice from the fact that their eyes are not jirovided with movable 

 eyelids (fig. 106). The Chamselons, also, cannot be said to possess 

 movable eyelids, for the eye is covered with a single lid, leaving only 

 a central ajjerture for the pupil. The common species {Cliamceleo 

 Afric'inus) occurs abundantly in the north of Africa, and has long 

 been known for the changes of colour which it has the power of ex- 

 hibiting. It is a sluggish animal, and catches insects by darting out 

 its long and worm-like tongue with extreme rapidity. 



Order IV. Crocodilia. 



The last and highest order of the living Reptiles is that of the 

 i'r<ii:odilia, comprising the Crocodiles, Alligators, and Gavials, and 

 characterised by the following peculiarities : The outer or integu- 



-A, Head .iiirl antfrior portion of the bnrly of Crocodilus pondicerionus ; 

 B, Hind-foot of the same. (AftLT Gunther.) 



mentary skeleton consists partly of horny scales developed by the 

 outer layer of the skin, and partly of large bony plates produced by 

 the imier layer of the skin (fig. 197). The bones of the skull and 



