10 ON THE LAW WHICH HAS REGULATED 
pagos Islands, which contain little groups of plants 
and animals peculiar to themselves, but most nearly 
allied to those of South America, have not hither- 
to received any, even a conjectural explanation. 
The Galapagos are a volcanic group of high anti- 
quity, and have probably never been more closely 
connected with the continent than they are at 
present. They must have been first peopled, like 
other newly-formed islands, by the action of winds 
and currents, and at a period sufficiently remote 
to have had the original species die out, and the 
modified prototypes only remain. In the same way 
we can account for the separate islands having each 
their peculiar species, either on the supposition that 
the same original emigration peopled the whole of 
the islands with the same species from which differ- 
ently modified prototypes were created, or that the 
islands were successively peopled from each other, 
but that new species have been created in each on 
the plan of the pre-existing ones. St. Helena is a 
similar case of a very ancient island having obtained 
an entirely peculiar, though limited, flora. On the 
other hand, no example is known of an island which 
can be proved geologically to be of very recent 
origin (late in the Tertiary, for instance), and yet 
possesses generic or family groups, or even many 
species peculiar to itself. 
When a range of mountains has attained a great 
elevation, and has so remained during a long geolo- 
gical period, the species of the two sides at and 
