242 Transactions. — Zoology. 



The fresh-water fish naturally supply more important evidence as to the 

 former distribution of land than those inhabiting the sea. Of these, New 

 Zealand possesses fifteen species, belonging to seven genera, of which six species, 

 or 40 per cent., and one genus^ are found nowhere else. That the percentage 

 of the endemic fresh-water fish should be nearly the same as that of the 

 marine fish is a remarkable and unexpected result, for the number of species 

 of marine fish inhabiting New Zealand and found also in other countries 

 depends partly on permanency of specific characters since New Zealand was 

 isolated, and partly on the power possessed by fishes of migrating to us from 

 other countries, while among the fresh-water fish the proportion depends 

 entirely on permanency of specific characters j consequently, this permanency 

 of specific characters must be greater in fresh-water than in salt-water fish, 

 and this is the more remarkable as our fresh-water fish are far more variable, 

 especially Galaxias attenuatus and Eleotris gobioides, than the marine, and 

 Galaxias attenuatus being found both in South America and Tasmania must 

 have had a longer specific existence than any of the others. It is therefore 

 evident that a great amount of variability is not inconsistent with great 

 specific longevity under certain conditions. The conditions in this case are, I 

 believe, the absence of any large rapacious fish preying on the smaller variable 

 ones, and thus tending to fix those varieties which are best adapted to elude 

 the observation of the enemy. These conditions will soon no longer exist in 

 our rivers on account of the introduction of the trout, and I should like to 

 draw attention to the fact that descriptions and figures of all the varieties of 

 fish occurring now in one or more of our rivers would be a most valuable 

 contribution to science as material for future naturalists. 



Of our fresh-water fish found beyond New Zealand, Retropinna richardsoni 

 is found in the Chatham Islands ; Galaxias fasciatus in both the Chatham and 

 Auckland Islands ; Galaxias attenuatus in the Chatham Islands, Tasmania, 

 Patagonia, and South America ; Galaxias olidus in Australia j Anguilla 

 auchlandii in the Auckland Islands ; Anguilla australis in the Auckland 

 Islands, Tasmania and Timor ; Anguilla latirostris in the Chatham Islands, 

 Europe, Egypt, China, and the West Indies ; Geotria australis in Australia ; 

 and Geotria chileiisis in Western Australia and Chile. Thus four of our fresh- 

 water fish are found in the Chatham Islands, and three in the Auckland 

 Islands, which are all the fresh-water fish known to inhabit those places ; three 

 are found in Australia, two in Tasmania, two in South America, one in the 

 Island of Timor, and one is spread from China to Europe and the West Indies. 

 The Australian grayling also {Prototroctes marcena), although a distinct 

 species, much resembles our own {P. oxyrhynchus) ; and another closely 

 related geuus {Haplochiton) is found in South America. 



The genus Eleotris is widely spread in tropical countries. Its head quarters 



