ANIMALS— PHYSICAL ENVIRONMENT 97 



Australia this species is able to excavate burrows in 

 soft soil. These it makes in sandy places in the 

 beds of temporary streams, and it reaches a layer of 

 damp sand even though the stream has been dry 

 for a long time. The burrows are not permanent ; 

 a fresh one is made for each day, and at night, when 

 the temperature is low and the humidity high, the 

 animal ascends to the surface to hunt for beetles. 



Heleioporus pictus is another burrowing form, but 

 it makes permanent burrows. In these it exists 

 for months at a stretch during periods of drought, 

 I am informed that the eggs are laid in the burrow, 

 about 18 inches deep in the sand, in a foamy mass. 

 Development occurs in the egg to such a stage that 

 the tadpole is ready to emerge as soon as rain faUs. 

 The albumen of the egg is hygroscopic, and when 

 moisture is abundant it is absorbed in such quantities 

 as to burst the membrane which covers the egg, and 

 release the tadpole. 



Chiroleptes platycephalus resembles the last species 

 in making a permanent burrow and in its abiHty to 

 exist in it through a long period of drought. It 

 possesses also remarkable powers of storing water, 

 and it can contain a very considerable quantity in 

 its urinary bladder, subcutaneous tissues, and peri- 

 toneal cavity ; when it is fully charged with water 

 it is almost spherical. It makes permanent burrows 

 to the depth of about a foot in soil which will shortly 

 be baked by the sun into a mass of hard clay, and 

 here it remains for the dry season. By means of 

 its burrowing and its powers of storing fluid it is 

 able to resist long droughts ; permanent springs and 



