352 
GEOGEAPHICAL DISTEIBUTIOX. 
Chap. XI. 
is also obvious that the individuals of the same species, 
though now inhabiting distant and isolated regions, must 
have proceeded from one spot, where their parents were 
first produced: for, as explained in the last chapter, it 
is incredible that individuals identically the same should 
ever have been produced through natural selection from 
parents specifically distinct. 
We are thus brought to the question which has been 
largely discussed by naturalists, namely, whether species 
have been created at one or more points of the earth’s 
surface. Undoubtedly there are very many cases of 
extreme difficulty, in understanding how the same spe¬ 
cies could possibly have migrated from some one point 
to the several distant and isolated points, where now 
found. Nevertheless the simplicity of the view that 
each species was first produced within a single region 
captivates the mind. He who rejects it, rejects the 
vera causa of ordinary generation with subsequent mi¬ 
gration, and calls in the agency of a miracle. It is 
universally admitted, that in most cases the area in¬ 
habited by a species is continuous; and when a plant 
or animal inhabits two points so distant from each 
other, or with an interval of such a nature, that the 
space could not be easily passed over by migration, the 
fact is given as something remarkable and exceptional. 
The capacity of migrating across the sea is more dis¬ 
tinctly limited in terrestrial mammals, than perhaps in 
any other organic beings ; and, accordingly, we find no 
inexplicable cases of the same mammal inhabiting dis¬ 
tant points of the world. No geologist will feel any 
difficulty in such cases as Great Britain having been 
formerly united to Europe, and consequently possessing 
the same quadrupeds. But if the same species [can 
be produced at two separate points, why do we not 
find a single mammal common to Europe and Aus- 
