GEOGRAPHY OF TIIE MALAY ARCHIPELAGO. 
181 
than one in the latter. Yet of the comparatively rich insect-fauna 
of Madeira, 40 per cent, are continental species ; and of the flower- 
ing plants more than 60 per cent. The Canary Islands offer 
nearly similar results. Nothing but a former connexion with the 
Continent will explain such an amount of specific identity (the 
weight of which will be very much increased if we take into account 
the representative species) ; and the direction of the Atlas range 
towards Teneriffe, and of the Sierra Nevada towards Madeira, are 
material indications of such a connexion. 
The Galapagos are no farther from South America than Ma- 
deira is from Europe, and, being of greater extent, are far more 
liable to receive chance immigrants ; yet they have hardly a species 
identical with any inhabiting the American continent. These 
islands therefore may well have originated in mid-ocean ; or if 
they ever were connected with the mainland, it was at so distant 
a period that the natural extinction and renewal of species has left 
not one in common. The character of their fauna, however, is more 
what we should expect to arise from the chance introduction of a 
very few species at distant intervals ; it is very poor ; it contains 
but few genera, and those scattered among unconnected families ; 
its genera often contain several closely allied species, indicating 
a single antitype. 
The fauna and flora of Madeira and of the Canaries, on the other 
hand, have none of this chance character. They are comparatively 
rich in genera and species ; most of the principal groups and 
families are more or less represented ; and, in fact, these islands do 
not differ materially, as to the general character of their animal and 
vegetable productions, from any isolated mountain in Europe or 
North Africa of about equal extent. 
On exactly the same principles, the very large number of species 
of plants, insects, and birds, in Europe and North America, either 
absolutely identical or represented by very closely allied species, 
most assuredly indicates that some means of land communication 
in temperate or sub-arctic latitudes existed at no very distant geo- 
logical epoch ; and though many naturalists are inclined to regard 
all such views as vague and unprofitable speculations, we are 
convinced they will soon take their place among the legitimate 
deductions of science. 
Geology can detect but a portion of the changes the surface of 
the earth has undergone. It can reveal the past histoiy and mu- 
tations of what is now dry land ; but the ocean tells nothing of her 
bygoue history. Zoology and Botany here come to the aid of 
