34 REPTILES 



added that the great water-monitor (Varanns salvator) of India 

 will, when frightened, occasionally rush headlong into the sea. 



Apart from the air and the ocean, the reptiles of the 

 present day have availed themselves of most stations suited to 

 their mode of life over the greater part of the earth with the 

 exception of the polar and sub-polar regions, although they 

 attain their maximum development, both as regards bodily 

 size and numbers, in the tropical and sub-tropical zones. 



Rivers and lakes, for example, are inhabited by various 

 kinds of fresh-water tortoises, belonging to several distinct 

 groups, among which the soft-tortoises, or Triony chides, are ex- 

 clusively aquatic, although they spend much of their time 

 basking on sand-banks. Many snakes, too, such as the 

 common British grass-snake {Tropidonotus natrix), the North 

 American water-mocassin (Ancistrodon piscivorus), and the huge 

 anaconda {Eunectes murinus) of South America, are in a greater 

 or less degree aquatic ; while several of the iguanas, and 

 especially the basilisk {Basiliscus americanus) likewise spend 

 much of their time in the water, as do some of the Old World 

 monitor lizards. 



A large number of reptiles have found safety from enemies 

 and an abundant food-supply by taking to an arboreal life. 

 Among such are the chamseleons, many geckos, a large number 

 of iguanas, and many Old World lizards. Among the latter 

 special attention may be directed to the so-called flying- 

 dragons {Draco) of the Malay countries, on account of the 

 membranous expansions by means of which they are enabled 

 to take long flying leaps from bough to bough. Many snakes, 

 such as the whip-snakes and the various kinds of tree-snakes, 

 are wholly arboreal ; while others, such as the pythons and 

 boas, spend much of their time on trees. Certain snakes are 

 also stated to take short journeys in the air, the natives of Borneo 

 attributing the power of flight to Chrosopelea ornata, C. 

 chrysochlora, and Dendrophis pictus ; and it appears that 

 these reptiles really can descend from a height in a manner 

 analogous to that practised by flying-squirrels. In the ventral 

 scales of these snakes there is a suture on each side, and by 

 muscular contraction these scales can be drawn inwards, so 

 that the whole lower surface becomes concave, and the body 

 may be compared to a split bamboo. 



