INTRODUCTION. 



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l ft 



naturally look for the strongest proofs in support of our theory, because the conditions there are 

 altogether more favourable. Let us first take the Chatham Islands, lying about four hundred 

 miles to the south-east of Wellington. It is very clear that there has been no land communica- 

 tion between the Chathams and New Zealand since the continental submergence. This has 

 allowed time for the production, by natural selection and the survival of the fittest, of several 

 distinct species. Now, let us see what we have. Notably, another species of Bell-bird (Anthornis 

 melanocephala) has come into existence — a much larger and finer species than our Korimako 

 (Anthornis melanura), although presenting the same adolescent and sexual phases of plumage. 

 But the curious thing about it is, that, side by side with this endemic species, our Bell-bird is also 

 to be found in the Chatham Islands and on the adjacent islets (Pitt Island and Mangare). To 

 my mind the only explanation of this phenomenon is the same that I have already given (' Trans. 

 N.Z. Inst.', vol. xxiv., p. 65) for the occurrence side by side of Cyanorhamphus unicolor and C. 

 erythrotis on Antipodes Island — namely, that the smaller species owes its existence there to a 

 comparatively-recent colonisation, the result of some accidental flight or migration from the 

 mainland, — with this difference : that in the case of Cyanorhamphus erythrotis the irruption of 

 the parent form must have been long anterior to the colonisation, so to speak, of the Chatham 

 Islands by the New Zealand Bell-bird, inasmuch as there has been time for a sufficient 

 modification of characters to entitle it (in the opinion of many ornithologists) to take specific 

 rank, distinct from Cyanorhamphus novcB-zealandice. As to such occasional migrations there 

 would be nothing in the distance, at any rate, to negative such a supposition. Then, again, we 

 have a Wood-pigeon (Hemiphaga chathamensis) very similar to the New Zealand bird, but 

 sufficiently differentiated to be accepted as a good species. Other representative forms are the 

 Black Bobin (Miro tr aver si), the Bush Warbler (Pseudogerygone albofrontata) , and the Chatham 

 Island Fern Bird (Bowdleria rufescens). The near relatives of all these are to be found in New 

 Zealand. Again, instead of Ocydromus, there is a small flightless Bail — a degenerate Ocydromine 

 form — which Professor Hutton has made the type of a new genus, Cabalus. To this genus 

 (although the form is less aberrant from the typical Ballas) I had also referred Dieffenbach's 

 Kail, which is now extinct, the only known example being the one in the British Museum, 

 obtained about the year 1845 ; but, for the reasons stated on page 45, I have now placed it 

 in the genus Nesolimnas. 



So far as we are aware, no bones of Binornis have yet been discovered in the Chatham Islands, 

 but I have no doubt that they will be met with sooner or later ; and I feel pretty sure that, when 

 discovered, they will be found to be of different species (perhaps of different genera ) from those 

 known to have inhabited New Zealand in comparatively recent times : that is to say, that our 

 theory seems to require, for the sake of consistency, that this should be so, inasmuch as the same 

 differentiation would be taking place in the Chatham Islands as in the other insular areas 

 after the great submergence. And, as the Chatham Islands unquestionably formed part of 

 that ancient continental area of which I have been speaking, we may reasonably expect to 

 find there, sooner or later, fossil remains of the earlier forms (such as Palapteryx), similar to 

 those that have been unearthed in the North and South Islands of New Zealand. As for the 

 remarkable avian remains discovered by Dr. H. 0. Forbes in the Chatham Islands, and referred 

 by him to a genus allied to Aphanapteryx, we may feel equally assured that similar remains 

 exist in New Zealand, and will hereafter be found in abundance to reward the diligent 

 explorer. 



The Auckland Islands, again, offer several good examples. Among the species specially 

 developed there may be mentioned a Ground-pipit (Anthus aucHandicus) , very readily dis- 

 tinguishable from our New Zealand bird by its rather larger size and warmer colouring; and 

 a Green Parrakeet (Cyanorhamphus auchlandicus) , much smaller, but in other respects similar 



