266 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



that has the power of changing its color to a considerable 

 degree and so is popularly called a chameleon. 



The group of lizards is a very large one, the species being 

 especially abundant in the tropics. The skin is covered with 

 many small scales, and the legs are fitted for running, but the 



FIG. 120. A fence lizard, Scdoporus accident alis. 



body is usually dragged along the ground and not wholly 

 lifted by the legs. The jaws are furnished with teeth. Lizards 

 feed principally upon insects, and some of the species may be 

 of considerable importance in controlling noxious forms. 

 Although the lizards are often regarded as being poisonous 



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FIG. 121. The Gila monster, Heloderma suspect unt, the only poisonous 



lizard. (After Snyder.) 



the members of only a single genus, Heloderma, are really so. 

 This genus includes the Gila monster found in New Mexico, 

 Arizona and northern Mexico. It is a heavy-bodied, deep 

 black, orange-mottled lizard, twelve to sixteen inches long. 

 The poison is secreted by glands in the lower jaw and flows 



