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 
Fic. 24.—TuHE 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 
