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We can here consider only a few cases; of these, some of the most difficult to explain are presented by fish. It was formerly believed that the same fresh-water species never existed on two continents distant from each other. But Dr. Gunther has lately shown that the Galaxias attenuatus inhabits Tasmania, New Zealand, the Falkland Islands and the mainland of South America.
I should prefer believing that the Galaxias was a species, like the Emys of the Sewalik Hills, which has long retained the same form.
I may add that there is an Indian toad which can resist salt water and haunts the seaside. Nothing ever astonished me more than the case of the Galaxias; but it does not seem known whether it may not be a migratory fish like the salmon. It seems to me that you complicate rather too much the successive colonisations with New Zealand.
It is however a coast fish, which, though entering rivers, yet lives in the sea. Eutropius is an African genus, but E. obtusirostris comes from India. On the other hand, Amiurus is a North American form; but one species, A. cantonensis, comes from China. The genus Galaxias has at least one species common to New Zealand and South America, and one common to South America and Tasmania.
These fishes, however, probably pass part of their lives in the sea. We thus certainly have several species which are common to the fresh waters of distant continents, although it cannot be certainly affirmed that they are exclusively and entirely fresh-water fishes throughout all their lives except in the case of Galaxias.
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