38 THE WANDERINGS OF ANIMALS [OH. 



Mongolia, which is unfavourable to amphibia, especi- 

 ally newts, a broad barrier which cannot be passed, 

 and there are none of them, except in China and 

 Burmah, south of this belt. Since these creatures 

 practically are restricted to the north of this belt, in 

 the Old World, we conclude that they had their 

 origin in the northern regions. 



In Australian deserts some of the few kinds of 

 Cystignathid toads burrow into the clay of the 

 drying-up water pans ; the clay becomes hard-baked, 

 and there they sleep until the next rains, when- 

 ever these may fall. Their whole body-cavity, many 

 subcutaneous spaces and the bladder are full of 

 water ; the body is swollen into a shapeless mass, 

 ugly, without any pretty coloration. When the rain 

 releases them, they at once spawn, the tadpoles 

 develop with great rapidity, soon to aestivate as tiny 

 frogs. The adult gorge themselves with caterpillars 

 and beetles which are then also swarming, and 

 thus they fatten themselves preparatory for the next 

 torpid season, which may be protracted for several 

 years owing to the uncertainty of the rains. The 

 Australian desert members of the genera Chiroleptes 

 and Heleioporus are always ready to spawn ; to miss 

 the opportunity would be disastrous to the race in 

 a country where the meteorological conditions are so 

 uncertain. 



Reptiles of the desert, to avoid the cold of the 



