lian mammalia, and almost all the most
characteristic Australian birds, insects, and plants. The form of the
sea-bed shows that the distance could not have been less than 600 miles,
even during the greatest extension of Southern New Zealand and Tasmania;
and we have no reason to suppose it to have been less, because in other
cases an equally abundant flora of identical species has reached islands at
a still greater distance--notably in the case of the Azores and Bermuda.
The character of the plants is also just what we should expect: for about
two-thirds of them belong to genera of world-wide range in the temperate
zones, such as Ranunculus, Drosera, Epilobium, Gnaphalium, Senecio,
Convolvulus, Atriplex, Luzula, and many sedges and grasses, whose
exceptionally wide distribution shows that they possess exceptional powers
of dispersal and vigour of constitution, enabling them not only to reach
distant countries, but also to establish themselves there. Another set of
plants belong to especially Antarctic or south temperate groups, such as
Colobanthus, Acaena, Gaultheria, Pernettya, and Muhlenbeckia, and these may
in some cases have reached both Australia and New Zealand from some now
submerged Antarctic island. Again, about one-fourth of the whole are alpine
plants, and these possess two advantages as colonisers. Their lofty
stations place them in the best position to have their seeds carried away
by winds; and they would in this case reach a country which, having derived
the earlier portion of its flora from the side of the tropics, would be
likely to have its higher mountains and favourable alpine stations to a
great extent unoccupied, or occupied by plants unable to compete with
specially adapted alpine groups. {504}

Fully one-third of the exclusively Australo-New Zealand species belong to
the two great orders of the sedges and the grasses; and there can be no
doubt that these have great facilities for dispersion in a variety of ways.
Their seeds, often enveloped in chaffy glumes, would be carried long
distances by storms of wind, and even if finally dropped into the sea would
have so much less distance to reach the land by means of surface currents;
and Mr. Darwin's experiments show that even cultivated oats germinated
after 100 days' immersion in sea-water. Others have hispid awns by which
they would become attached to the feathers of birds, and there is no doubt
this is an effective mode of dispersal. But a still more