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 chamzleon, 
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. 
