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 flying 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-limb 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 familiar 
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 
