THE CONQUEST OF THE DRY LAND 211 



tree-toads lay their eggs in a damp hole in a 

 tree, and one of them makes a leaf-nest on 

 branches overhanging the water, and arranges 

 matters so that the bottom falls out and lands 

 the contents in the water just as the eggs are 

 turning into tadpoles. The harvest-mouse 

 fastens to the wheat stems its lightly built nest 

 of twined leaves of grass. We must not in- 

 clude the nests of animals like squirrels, which 



FIG. 24. THE AUSTRALIAN DUCKMOLE (ORNITHORHYNCHUS). 

 An old-fashioned Mammal that lays two eggs in a well- 

 hidden nest in a Burrow beside a Pool. 



have ceased to be terrestrial in the strict sense, 

 or the nests of flying birds and thoroughly 

 aerial insects like wasps. 



A third way of securing the safety of the 

 young ones is to keep them for a long time 

 within the shelter of the mother's body, and 

 perhaps to carry them about after they are 



