CHAP. XIII.] THE AUSTRALIAN REGION. 401 



fishes, as of plants and insects, lias undoubtedly occurred, but 

 this has been effected by other means. If we look at a globe 

 WG 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 Xew 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 JMacquaries' group. Emerald Island, is only (300 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 tliat 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 miglit 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 intercommimication 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 all these remote 

 lands within the period of existence of this one species of fish, 



