CHAP. XIII. ] THE AUSTRALIAN REGION. 401 
fishes, as of plants and insects, has undoubtedly occurred, but 
this has been effected by other means. If we look at a globe 
we see at once how this interchange may have taken place. 
Immediately south of Cape Horn we have the South Shetland 
Islands and Graham’s land, which is not improbably continuous, 
or nearly so, with South Victoria land immediately to the south 
of New Zealand. The intervening space is partly occupied 
by the Auckland, Campbell, and Macquaries’ Islands, which, 
there is reason to believe are the relics of a great southern ex- 
tension of New Zealand. At all events they form points which 
would aid the transmission of many organisms ; and the farthest 
of the Macquaries’ group, Emerald Island, is only 600 miles from 
the outlying islets of Victoria land. The ova of fish will survive 
a considerable time in the air, and the successful transmission of 
salmon ova to New Zealand packed in ice, shows how far they 
might travel on icebergs. Now there is evidently some means 
by which ova or young fishes are carried moderate distances, from 
the fact that remote alpine lakes and distinct river systems often 
have the same species. Glaciers and icebergs generally have pools 
of fresh water on their surfaces ; and whatever cause transmits fish 
to an isolated pond might occasionally stock these pools, and by 
this means introduce the fishes of one southern island into 
another. Batrachians, which are equally patient of cold, might 
be transported by similar means; while, as Mr. Darwin has so 
well shown, (Origin of Species, 6th Ed. p. 345) there are various 
known modes by which plants might be transmitted, and we 
need not therefore be surprised that botanists find a much 
greater similarity between the production of the several Southern 
lands and islands, than do zoologists. It is important to notice 
that, however this intercommunication was effected, it has con- 
tinued down to the epoch of existing species; for Dr. Giinther 
finds the same species of fresh-water fish (Galaxias attenuatus) 
inhabiting Tasmania, New Zealand, the Falkland Islands, and 
Temperate South America ; while another species is common to 
New Zealand and the Auckland Islands. We cannot believe 
that a land connection has existed between al] these remote 
lands within the period of existence of this one species of fish, 
