THE ENQUIRY DEFINED. 
293 
There are two methods of considering the Natural 
History of a given spot, each having its peculiar 
advantages. We may investigate it with regard 
only to those phenomena and circumstances pro¬ 
perly and peculiarly its own, irrespectively of all 
interferences and additions by the inroads of agri¬ 
culture, planting, &c.; or we may consider it in its 
present state under all its alterations. The first mode 
has the advantage of being the more natural, and 
it is also calculated to display a great number of 
remarkable features of the spot. The second plan 
has the advantage of setting things in their present 
light, and serves also to show to what extent 
animals are influenced by our proceedings, how 
far their distributions are modified by our advances 
and operations, the instincts guiding them in their 
defences against our intrusions, and lastly, it serves 
to demonstrate an important principle in the eco¬ 
nomy of a great proportion of creatures, that namely 
of adaptation to variety in surrounding conditions, 
a quality almost unrestricted in the human species 
but enjoyed in a more limited degree by the lower 
animals, without which however their lives would 
be dependent upon the slightest alterations in sur¬ 
rounding circumstances, and without which we 
should not have been enabled to subject any of 
them to our uses and pleasures. I believe it will 
be expedient to examine the Zoology of this dis¬ 
trict with reference both to original and to existing 
features, giving to each its respective value and 
peculiar considerations. 
We include in our local survey that portion 
of Devonshire which extends from the heart of 
Dartmoor to the southern coast, and which is 
included between the rivers Exe and Tamar re¬ 
spectively on the east and west. There is thus 
presented to the view an extent of country having 
in its northern part the character of sterility, and 
