470 SUBANTARCTIC ISLANDS Ol' NEW ZEALAND. [Systematic Botany. 



this very important point. I am informed, however, that the geologists attached 

 to the expedition concerning which this series of memoirs has been prepared found 

 unmistakable evidence of recent glaciation on an extensive scale, although not 

 sufficient to prove that the islands were covered by a continuous ice-cap. But a 

 more severe climate than that which now exists must have adversely affected the 

 phanerogamic flora. We can hardly expect that an arboreal vegetation could exist 

 under such circumstances, or that we should find such a large proportion of 

 pteridophytes as is now the case. It is a suggestive fact that the whole of the 

 shrubby vegetation of the islands, with the single exception of Olearia Lyallii, 

 which is so closely allied to the New Zealand 0. Colensoi as to be looked upon as 

 a recent derivate form, consists of species living at the present time in New Zea- 

 land, and that the same is the case with the pteridophytes. In all probability the 

 endemic species, or that portion of them to which I have applied the name of the 

 " Stilbocar'pa-PleurophyUum group," were the only survivors of this period of glaci- 

 ation. The remainder of the present flora, mostly consisting of species either living 

 in New Zealand at the present time or closely allied to such, must be looked upon 

 as immigrants which made their appearance in the islands when the climatic con- 

 ditions became more favourable. 



But any cold period which existed in the Auckland and Campbell Islands must 

 have been much more severely felt in Macquarie Island, lying more than 2 degrees 

 to the south of Campbell Island. Unfortunately, no geological exploration has ever 

 been made of this remote outlier of the southern islands ; but it is impossible to read 

 the descriptions of its physical features given by Dr. Scott and Mr. Hamilton without 

 suspecting that it has been heavily glaciated within a recent period, and possibly 

 covered with an almost continuous ice-sheet. I regard it as almost certain that 

 during this period of glaciation the phanerogamic flora perished, with the exception 

 of two or three grasses ; and that the present vegetation, obviously a collection of 

 waifs and strays, has since arrived through trans-oceanic migration — some, in accord- 

 ance with the direction of the prevailing westerly winds, from Kerguelen ; the re- 

 mainder from the much nearer Auckland and Campbell Islands. Under this view, 

 the chief peculiarities of its flora receive a probable explanation. We can understand 

 the presence of the Fuegian and Kerguelen Azorella Selago and Ranunculus hiternatus, 

 which have failed to reach any other of the southern islands ; and we can recognise 

 that Macquarie Island may have been an important stepping-stone in other migra- 

 tions of an older date to the southern islands, or even to New Zealand. 



In conclusion, I desire to express my great indebtedness to the following authors, 

 from whose writings I have drawn many of the facts upon which this memoir is 

 based. First of all, to Sir Joseph Hooker, whose splendid " Flora Antarctica " must 

 always remain the foundation of our knowledge of the vegetation of those land-areas 

 which most nearly approach the south polar regions, and whose speculations on the 

 origin and distribution of southern floras have illuminated the path of all subsequent 

 workers. Also to Dr. A. E. Wallace, whose " Geographical Distribution of Animals," 

 and particularly his " Island Life," contain much original matter and many valuable 

 suggestions bearing on the origin and relationships of the New Zealand fauna and 

 flora. Captain Hutton's memoirs on the " Origin of the Fauna and Flora of New 

 Zealand " and on the " Geological History of New Zealand " have been of great use 

 to me. I am also much indebted to Dr. Cockayne's paper " On a Botanical Excursion 



