230 THE HAUNTS OF LIFE 



situation, but, as a matter of fact, getting up a 

 tree has often meant a progressive step in the 

 history of animal life. It opens up new pos- 

 sibilities of movement, of feeding, of nesting, 

 and so forth, and it is a portal which many 

 different kinds of animals have tried to enter. 

 Even earthworms have been found up trees, 

 and the land-leeches often drop from the 

 branches. Many insects and spiders are ar- 

 boreal, and the Robber-Crab climbs the coco- 

 palm for nuts. The skip-jack, Periophthal- 

 mus, climbs on the roots of the mangroves, 

 and there are many tree-toads. Among reptiles 

 there are arboreal lizards like the chamaeleon, 

 so admirably suited to the branches in having 

 a prehensile tail and both its hands and its 

 feet cleft into two halves for gripping pur- 

 poses. Then there are green and agile tree- 

 snakes. Many birds and mammals are strictly 

 arboreal, and, in the case of monkeys, the per- 

 fecting of the arboreal habit has led to the 

 emancipation of the hand. For when the 

 fore-limb was no longer needed as a support- 

 ing member, it became an instrument for 

 touching and grasping, for handling and lift- 

 ing. And when monkeys got a free hand they 

 also got a nimbler brain. 



