| →OMIT
Great Britain
→OMIT
possessing the same
→quadrupeds with the rest of Europe, for they were no doubt once united. But if the same species can be produced at two separate points, why do we not find a single mammal common to Europe and
or South America? The conditions of life are nearly the same, so that a multitude of European animals and plants have become naturalised in America and Australia; and some of the aboriginal plants are identically the same at these distant points of the northern and southern hemispheres? The answer, as I believe, is, that mammals have not been able to migrate, whereas some plants, from their varied means of dispersal, have migrated across the
and broken
The great and striking influence
barriers of
→all kinds,
is intelligible only on the view that the great majority of species have been produced on one
and have not been able to migrate to the
side. Some few families, many sub-families, very many genera, and a still greater number of sections of
are confined to a single region; and it has been observed by several naturalists, that the most natural genera, or those genera in which the species are most closely related to each other, are generally
→confined to the same country, or if they have a wide range that their range is continuous. What a strange anomaly it would
→be, if a directly opposite rule were to prevail, when we go down
one step lower in the series,
the individuals of the same species,
→and these had not been, at least at first, confined to some one region!
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