8 HISTORICAL RECORD 



These 34 genera are represented by 236 species, all but one of 

 them being endemic, viz., Ophicardelus australis, which is also found 

 in Tasmania, Australia and New Caledonia. Planorbis corinna which 

 is world- wide in its distribution is precinctive to New Zealand, but 

 the genus Planorbis has a universal distribution. 



Mr Suter informs me that "the genera of land mollusca which 

 we have in common with Tasmania and Australia are far better 

 represented in the former country, but disappear gradually as the 

 north-east is reached. The affinities of our land and fresh- water 

 molluscs are strongly marked on the line extending over Lord Howe 

 Island to New Caledonia." 



The relationship of New Zealand insects to those of other regions 

 is dealt with in a number of papers scattered through many publica- 

 tions, but the knowledge of the subject is still very fragmentary. 

 Meyrick, in his papers on Lepidoptera, favours the theory of introduc- 

 tion of several groups (e.g. Caradrinina) from South America via 

 Antarctica. But leaving the general question and confining myself 

 to species derived from the nearest present land surface, the following 

 summary of the distribution of the Lepidoptera, for which I am 

 indebted to Mr A. Philpott, is of interest : 



Total number of species hitherto recorded in New Zealand . . . 1040 



Common to Australia and New Zealand 63 



Cosmopolitan species ? 24 



Introduced from Australia to N.Z., by shipping (say) ... 6 

 Introduced to Australia from N.Z., by shipping (say) ... 3 



33 



Leaving for the question of origin, only 30 species, or say, 3 per cent, 

 common to both countries. 



These figures are not very conclusive one way or another. 



The nearest land-surface of any extent is the continent of Australia 

 and, as might be expected, immigrants from thence are by no means 

 uncommon. Within the last score or so of years a great many species 

 of Australian birds have been recorded as occasional visitants to New 

 Zealand. The same remark applies to some of the stronger flying 

 insects. This shows that though the fauna recognised as indigenous 

 has originally been introduced from several directions in former 

 ages, there has been and still is a constant stream of immigrants 

 from Eastern Australia into these islands. The remarkable thing then 

 is that there should be so comparatively little direct connection 

 between the two countries so far as the fauna is concerned. The fact 

 is that it is very difficult for a species of animal to establish itself 

 in a new country, even assuming that many individuals arrive at 



