THE EVOLUTION OF THE BIRDS 451 



fear from other animals. Their degeneracy was therefore, so 

 to speak, allowed because of the greater leniency of natural 

 selection in these regions. 



Literature 



Heilmann, G. The Origin of Birds. Witherby, London, 1926. 

 Pycraft, W. P. A History of Birds. Methuen, London, 1910. 



