CHAPTER II 



THE ELEMENTARY FACTS OF DISTRIBUTION 



Importance of Locality as an essential character of Species — Areas of Dis- 

 tribution — Extent and Limitations of Specific Areas — Specific range of 

 Birds — Generic Areas — Separate and overlapping areas — The species of 

 Tits as illustrating Areas of Distribution — The distribution of the species 

 of Jays — Discontinuous generic areas — Peculiarities of generic and 

 family distribution — General features of overlapping and discontinuous 

 areas — Restricted areas of Families — The distribution of Orders. 



So long as it was believed that the several species of 

 animals and plants were " special creations," and had been 

 formed expressly to inhabit the countries in which they are 

 now found, their habitat was an ultimate fact which re- 

 quired no explanation. It was assumed that every animal 

 was exactly adapted to the climate and surroundings amid 

 which it lived, and that the only, or, at all events, the chief 

 reason why it did not inhabit another country was, that 

 the climate or general conditions of that country were not 

 suitable to it, but in Avhat the unsuitability consisted we 

 could rarely hope to discover. Hence the exact locality of 

 any species was not thought of much importance from a 

 scientific point of view, and the idea that anything could 

 be learnt by a comparative study of different floras and 

 faunas never entered the minds of the older naturalists. 



But so soon as the theory of evolution came to be gener- 

 ally adopted, and it was seen that each animal could only 

 have come into existence in some area where ancestral 



