t the Antarctic continent, and the prevalent winds are also
westerly. No doubt, however, there are occasional storms, and there may
have been intermediate islands, but its chief advantages are its antiquity,
its varied surface, and its favourable soil and climate, offering many
chances for the preservation and increase of whatever plants and animals
have chanced to reach it. The island consists of basalt, greenstone, and
other ancient rocks, and though only about twelve miles long its mountains
are three thousand feet high. Enjoying a moist and temperate climate it is
especially adapted to the growth of ferns, which are very abundant; and as
the spores of these plants are as fine as dust, and very easily carried for
enormous distances by winds, it is not surprising that there are nearly
fifty species on the island, while the remote period when it first received
its vegetation may be indicated by the fact that nearly half the species
are quite peculiar; while of 102 species of flowering plants seventy are
peculiar, and there are ten peculiar genera. The same general character
pervades the fauna. For so small an island it is rich, containing four true
land-birds, about fifty species of insects, and twenty of land-shells.
Almost all these belong to South American genera, and a large proportion
are South American species; but several of the insects, half the birds, and
the whole of the land-shells are peculiar. This seems to indicate that the
means of transmission were formerly greater than they are now, and that in
the case of land-shells none have been introduced for so long a period that
all have become modified into distinct forms, or have been preserved on the
island while they have become extinct on the continent. For a detailed
examination of the causes which have led to the modification of the humming
birds of Juan Fernandez see the chapter on Humming Birds in the author's
_Natural Selection and Tropical Nature_, p. 324; while a general account of
the fauna of the island is given in his _Geographical Distribution of
Animals_, Vol. II. p. 49.

[116] No additions appear to have been made to this flora down to 1885,
when Mr. Hemsley published his _Report on the Present State of our
Knowledge of Insular Floras_.

[117] _Journal of the Linnean Society_, Vol. XIII., "Botany," p. 556.

[118] _Geographical Distribution of Animals_, Vol. II. p. 81.

[119] _St. Helena: a Physical, Historical, and Topographical Description of