others of their kind blown out to sea accidentally--for only such
species were likely to arrive there--and this kept up the purity of the
original race, by ensuring a cross every now and again with the
European community. But the bullfinches, being the merest casuals,
never again to my knowledge were reinforced from the mainland, and so
they have produced at last a special island type, exactly adapted to
the peculiarities of their new habitat.

You see, there was hardly ever a big storm on land that didn't bring at
least one or two new birds of some sort or other to the islands.
Naturally, too, the newcomers landed always on the first shore they
could sight; and so at the present day the greatest number of species
is found on the two easternmost islands nearest the mainland, which
have forty kinds of land-birds, while the central islands have but
thirty-six, and the western only twenty-nine. It would have been quite
different, of course, if the birds came mainly from America with the
trade winds and the Gulf Stream, as I at first anticipated. In that
case, there would have been most kinds in the westernmost islands, and
fewest stragglers in the far eastern. But your own naturalists have
rightly seen that the existing distribution necessarily implies the
opposite explanation.

Birds, I early noticed, are always great carriers of fruit-seeds,
because they eat the berries, but don't digest the hard little stones
within. It was in that way, I fancy, that the Portugal laurel first
came to my islands, because it has an edible fruit with a very hard
seed; and the same reason must account for the presence of the myrtle,
with its small blue berry; the laurustinus with its currant-like fruit;
the elder-tree, the canary laurel, the local sweet-gale, and the
peculiar juniper. Before these shrubs were introduced thus