3 i8 ELEMENTARY ZOOLOGY 



tive spiny protuberances, and in individual color and 

 pattern resembles closely the soil, rocks, and cactus among 

 which the particular horned toad lives. All the species 

 of PJirynosoma are viviparous, seven or eight young being 

 born alive at a time, 



In New Mexico, Arizona, and northern Mexico the only 

 existing poisonous lizards, the Gila Monster (Helodcrma) 

 (fig. 126) is found. This is a heavy, deep-black, orange- 

 mottled lizard about sixteen inches long. There is much 

 variance of belief among people regarding the Gila Mon- 

 ster, but recent experiments have proved the poisonous 

 nature of the animal. The poison which is secreted by 

 glands in the lower jaw flows along the grooved teeth into 

 the wound. A beautiful and interesting little lizard found 

 in the South is the green chameleon (Anolis principalis}. 

 Its body is about three inches long with a slender tail of 

 five or six inches. The normal color of the chameleon is 

 grass-green, but it may "assume almost instantly shades 

 varying from a beautiful emerald to a dark and iridescent 

 bronze color. " 



In the tropics many of the lizards reach great size and 

 are of strange shape and patterns. The flying dragons 

 (Draco] have a sort of parachute on each side of the body 

 composed of a fold of skin supported by five or six false 

 .posterior ribs. These lizards live in the trees of the East 

 Indies and "fly" or sail from tree to tree. They are 

 very beautifully colored. The iguanas (Iguana) of the 

 tropics of South America are commonly used for food. 

 They live mostly in trees, and reach a length of five or 

 six feet. The monitor ( Varanus niloticus) is a great 

 water-lizard that lives in the Nile, and feeds on crocodiles' 

 e gg s > of which it destroys great numbers. It is the prin- 

 cipal enemy of the crocodile. When full grown it reaches 

 a length of six feet or even more. 



About 1,000 living species of snakes are known.. 



