718 EVOLUTION OF ANIMALS Part V 



Order Squamata. Lizards and snakes. 

 Order Crocodilia. Crocodiles and alligators. 

 Order Chelonia. Turtles and tortoises. 



Order Squamata — Lizards and Snakes 



These reptiles have certain distinguishing structures not intelligible without 

 special study. The two suborders are easy to separate, since lizards have legs 

 and snakes do not. However, there are a few limbless lizards which cannot be 

 distinguished from snakes except by internal structures. 



Lizards. In general, lizards are clean vigorous carnivores that earn their 

 way in the living web of their community. All are interesting. Many are beauti- 

 ful. The little geckos, numerous in hot countries, run about at night often on 

 the walls of houses, even on the ceilings to which they hold tightly by their 

 sticky toe pads (Fig. 35.5). In the flying dragons of the East Indies, the ribs are 



Fig. 35.5. Common wall gecko (Tarentolo mauritanicus) of southern Europe. 

 Length, 6 inches. Geckos are a large group of lizards, four of them native to 

 the southern United States. Their sticky toe pads enable them to walk on ceilings. 

 (Courtesy, Guide to the Reptile Gallery, British Museum.) 



extended beyond the sides of the body and covered by folds of skin that serve 

 as wings enabling their owners to take gliding flights from branch to branch 

 (Fig. 35.6). The wings are gorgeously colored and flying dragons are sugges- 

 tive of brilliant butterflies. 



Chameleon is the common name of one of the most remarkable of the 

 families of lizards (Fig. 35.7). Because of their ability to change color the 

 same name is also applied to the chameleons (Anolis) of the southern United 

 States. The true chameleon however is found in Africa, Arabia, and southern 

 India. In it, the toes are joined together in two bundles; with these and its 

 prehensile tail it is a truly non-slip climber of extraordinary agility. It can 

 thrust out its tongue more than the length of its body, aim with accuracy and 

 bring back a fly on the sticky tip, all in motions too fast for the eye to follow 

 clearly. Its ability to change color receives more than its share of fame for it 

 is equaled or surpassed in this by other species. The lizards found in the 

 United States include the horned lizard or "horned toad" (Phrynosoma) of 

 the Great Plains and Rocky Mountains (Fig. 35.1); and one of the only two 



