xiv DISTRIBUTION 601 



between the marine Fishes, though obvious enough, are less 

 fundamental, a fair proportion of the New Zealand shore-fishes 

 belonging to the same families, and in some cases even to the 

 same genera and species, as those of Britain. 



Among Mollusca the fresh-water Unio (fresh-water Mussel) is 

 found in both countries, but New Zealand has no species of the 

 common genus Helix (Land-snail), abundant in Great Britain, and 

 its molluscan fauna generally is very peculiar. 



The Insect-fauna of New Zealand is remarkable for the paucity 

 of Butterflies sixteen species against about seventy in Britain 

 and for the abundance of Moths, mostly belonging to the Micro- 

 lepidoptera and the Geometrina. The occurrence of Peripatus in 

 New Zealand furnishes another strong point of contrast. Amongst 

 fresh-water Crustacea, the British Astacus is represented by an 

 allied genus Paranephrops. Among marine Crustacea many genera 

 are common to the two countries, but there are numerous 

 peculiar forms, and it is worthy of mention that the New Zealand 

 species of Palinurus belongs to a more generalised type than the 

 British species, having no stridulating organ. 



The British Earthworms all belong to the familiar Lumbricidce 

 (including Lumbricus) and Cryptodrilidce ; in New Zealand both 

 these families are absent, and the majority of the Earthworms 

 belong to the Megascolecidse, including the genera Acanthodrilus, 

 Octochcetus, &c. Lastly, there are found in New Zealand nearly 

 forty species of Land Planarians and one terrestrial Nemertean ; 

 these groups are represented in the land-fauna of Britain only by 

 one species of the former. 



That these striking differences are quite independent of climate, 

 food, &c. in other words, that the environment in the one country 

 is in no way inimical to the fauna of the other is shown by the 

 zoological history of New Zealand since its colonisation. Apart 

 from domestic animals, the Brown Rat (Mus decumanus) and the 

 House Mouse (Mus domesticus) are now as common in New 

 Zealand as in Britain ; the Rabbit has become a plague, barely 

 kept in check by constant effort stimulated by severe legislative 

 enactments ; Deer flourish as well in the mountains of Otago as 

 in those of Scotland ; the Birds first noticed by a visitor to the 

 settled districts of the colony will probably be the Sparrow, Black- 

 bird, Thrush, Starling, and Goldfinch ; and Trout have become 

 so thoroughly acclimatised in the streams and lakes, that in some 

 districts the poorer settlers, like the British apprentices of old, 

 decline to eat them. We thus learn to distinguish between the 

 native or indigenous fauna of a country and the introduced fauna 

 which owes its existence to human agency ; in comparing the 

 faunae of any two countries, the latter element must of course be 

 carefully eliminated. 



