LA.CERTIA OR LIZARDS. 



225 



tropical regions, have toes provided with a flattened disk 

 which enables them to crawl up walls and even along the 



FIG. 257. 



Gecko. 



ceilings with the back downwards. Some, like the 

 "Horned Toads" of Western North America, are armed 



FIG. 258. 



Horned Toad, Phrynosoma cnrnula, Gray. 



with tubercles and spines. Others, as the Chameleons of 

 the Old World, have the tail prehensile, the tongue fleshy 

 and extensible, the eyes large and covered with skin, ex- 

 cept a small hole opposite the pupil, and possessing the 

 faculty of moving independently of each other! 



Other lacertians still, as the Glass-snakes of the Mis- 

 sissippi valley, are snake-like in general appearance, having 

 no external locomotive members. They received their 



10* 



