THE ANIMAL CLIMAX-THE CHORDATES 



327 



Fig. 13-46. One of the largest lizards alive today, Iguana iguana, reaches a length of 6 feet. It inhabits tropical 



America. 



man or because he inherits a fear of them, 

 but because he is taught to be afraid of 

 them, particularly snakes. The group as a 

 whole does little harm to man or his 

 domestic animals, and what harm is done is 

 offset by its creditable deeds. 



Both lizards and snakes are covered with 

 scales which they shed periodically. 



The lizards are four-legged animals and 

 exemplify the typical modern reptile, that 

 is, they show the least amount of modifica- 

 tion in body form of any of the reptiles. A 

 good example of the group is the Iguana 

 (Fig. 13-46). The group contains rather 

 bizarre types, among them the horned toad 

 (Fig. 13-47) and the tree-dwelling chame- 

 leon. The latter possesses a prehensile tail 

 and feet that have three fused toes oppos- 

 ing the other two, an ideal adaptation for 

 arboreal life. It also has the ability to 



change its color rapidly, a characteristic not 

 confined to reptiles alone by any means. 

 However, this lizard does show a greater 

 extreme in color change than most other 

 animals. It also has a protrusible tongue 

 almost equal to its body in length, a con- 

 venient tool for catching insects. The only 

 poisonous lizard is the Gila monster (Fig. 

 13-47), a highly colored, sluggish, plump 

 creature found in various desert regions of 

 the world. It uses its venom in killing small 

 animals which make up its diet. Its bite is 

 rarely, if ever, fatal to man. The venom 

 flows into the wound from the base of the 

 teeth as a result of chewing action; this is 

 a far less efficient mechanism than that of 

 the snakes. 



The lowly snake is forever pursued and 

 killed by mankind the world around. It is 

 feared and hunted because some members 



