116 THE FAUNA OF 



animals caught under water till death takes place, 

 the crocodile being meantime protected from choking 

 by the nature of the internal nostrils. 



Of the lizards the flying forms (Draco) are interest- 

 ing. They occur in the Indo-Malayan countries, and 

 their parachute is a lateral fold of skin supported upon 

 the posterior ribs, which are greatly elongated. The 

 mechanism is thus entirely different from that seen in 

 any flpng mammal. The body is greatly depressed, 

 and the ' wings ' when not in use are folded close to 

 the body. 



The iguanas of tropical America and the West Indies 

 are also arboreal forms, but show no special adapta- 

 tions to this mode of life. They haunt especially trees 

 overhanging water, and are said to have the curious 

 habit of dropping into the water with a splash, some- 

 times from a great height, if alarmed. The most purely 

 arboreal of the lizards are, however, the chameleons, 

 specially characteristic of Africa, but also found in 

 India and Ceylon, and extending into Europe in Spain. 

 All have prehensile tails, and the hands and feet con- 

 stitute perfect grasping organs. The limbs . are long 

 and slender, the forelegs especially so. The fingers and 

 toes form two groups, two being opposed to the other 

 three. On the fore-hmb the first three fingers form an 

 inner bundle opposed to the fourth and fifth, which 

 are outside. In the foot the inner bundle is made up 

 by the first two toes only, the third, fourth, and fifth 

 forming the outer group. The animals are insecti- 

 vorous, and their power of colour-change is famiUar 

 to all. 



Of the snakes the tree boas of South America are 

 forest-haunting forms, with prehensile tails, and feed 

 chiefly upon birds. Like their allies the pythons and 



