THE MASTERY OF THE AIR 263 



collapsed umbrella. When it is going to " fly " 

 the ribs are extended and form the supports 

 of a fine parachute. The dragon can swoop 

 several yards, sometimes to avoid an enemy, 

 sometimes after a swarm of insects. The 

 upper surface of the body is brightly coloured, 

 and there is a curious dewlap on the throat. 



There is another tree-lizard, Ptychozoon, 

 whose long tail bears a scolloped fringe of skin 

 on each side, and this again helps in swooping. 

 There is a tree-snake (Dendrophis) which dis- 

 dains all accessories and launches itself stiffly 

 from a lofty branch to the ground. But is 

 there anything in the way of movement a snake 

 cannot do except cross a sheet of ice or Ahorse- 

 hair rope ? 



(D) What bats achieved many mammals 

 have attempted, that is, if we regard parachut- 

 ing as on the way towards flight. It is note- 

 worthy that all the attempts at flight among 

 mammals have been made in families that are 

 arboreal in habit, so that climbing tall trees may 

 have been the first step towards acquiring 

 wings or some substitute for them. Thus we 

 have the flying phalangers of New Guinea and 

 Australia, including many species, "the largest 

 of which is as big as a cat, while the smallest is 



