BRANCH CHORD AT A : CLASS REPTIL1A 3*7 



and often fear on the part of the natives of tropical lands. 

 In those regions are current extraordinary stories and 

 beliefs regarding the habits and attributes of certain lizards 

 like the basilisk and chameleon. Lizards are all more or 

 less elongate and some are truly snake-like in form. The 

 legs, though usually present and functional, are in many 

 cases much reduced, and in some forms, as the glass- 

 snake, either one or both pairs are so rudimentary as to 

 have no external projection whatever. Although lizards 



FlG. 126. The Gila monster, Heloderma horridum* the only poisonous 

 lizard. (Photograph from life by J. O. Snyder. 



are often regarded as being poisonous, only one genus, 

 Hcloderma, the Gila Monster, is really so. All others 

 are perfectly harmless as far as poison is concerned, and 

 most of them are unusually timid. They vary in size from 

 a few inches to six feet in length. Most of them are ter- 

 restrial, some arboreal, and some aquatic. 



Among the lizards of this country the swifts and ground- 

 lizards are familiar everywhere. In certain regions the 

 glass-snake or joint-snake (Opheosaurus vcntralis) is 

 common. This animal, popularly considered to be a 

 snake, has no external limbs, and its tail is so brittle, the 

 vertebrae composing it being very fragile, that part of it 

 may break off at the slightest blow. In time a new tail 

 is regenerated. It Jives in the central and northern part 

 of the United States, and burrows in dry places. In the 

 western part of the country horned toads {Phrynosoma} 

 are common, about ten different species being known. 

 These are lizards with shortened and depressed body and 

 well-developed legs. The body is covered with protec- 



