98 Transactions. — Zoology. 



the case of Platycercus erythrotis the irruption of the parent 

 form must have been long anterior to the colonization, 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 ornitholo- 

 gists) to take specific rank, distinct from Platycercus novce- 

 zealandia. As to such occasional migrations there would be 

 nothing in the distance, at any rate, to negative such a sup- 

 position. Then, again, we have a Wood-pigeon (Garpopliaga 

 cliathamiensis) very similar to the New Zealand bird, but 

 sufficiently differentiated to be accepted as a good species. 

 Other representative forms are the Black Robin (Miro traversi), 

 the Bush Warbler {Gerygone albofrontata) , and the Chatham 

 Island Fern-bird (S-phcnceacus rufescens). The near relatives 

 of all these are to be found in New Zealand. But, instead of 

 Ocydromus, there is a small flightless rail — a degenerate Ocy- 

 dromine form — which Professor Hutton has made the type of 

 a new genus, Cabalus modesties. To this genus (although the 

 form is less aberrant from the typical Ballus) I have referred 

 Dieffenbach's Eail, which is now extinct, the only known 

 example being the one in the British Museum, obtained about 

 the year 1845. 



So far as we are aware no bones of Dinornis have yet been 

 discovered in the Chatham Islands, but I have no doubt that 

 they will be sooner or later ; and I feel pretty sure that when 

 discovered they will be found to be of different species (per- 

 haps of different genera) from those known to have inhabited 

 New Zealand in comparatively recent times : that is to say, 

 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 in- 

 sular areas after the great submergence. And, as the Chat- 

 ham 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 to the remarkable avian remains recently dis- 

 covered by Mr. H. 0. Forbes in the Chatham Islands, and 

 referred by him to a genus allied to Arcliceoptcryx, we may 

 feel equally assured that similar remains exist in New Zea- 

 land, 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 aucklandicus) , very readily distinguish- 

 able from our New Zealand bird by its rather larger size and 

 warmer colouring ; and a Green Parrakeet (Platycercus auch- 



