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 required no explana- 
tion. 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 con- 
ditions of that country were not suitable to it, but in what 
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 generally 
adopted, and it was seen that each animal could only have 
come into existence in some area where ancestral forms closely 
allied to it already lived, a real and important relation was 
