Manchester Memoirs, Vol. xlvi. (1902), No. X^. 15 



New Zealand Sub-region. This condition is supposed to 

 have lasted on into Pleistocene times, and to have been 

 followed by another depression, which left the islands 

 very much in their present condition. 



The former land connection thus roughly sketched 

 out, together with the ocean current already referred to, 

 would be quite sufficient to account for the great 

 resemblances between the fauna and flora of the Chatham 

 Islands and those of New Zealand proper. Indeed, it is 

 the differences rather than the resemblances which require 

 explanation, and there appear to be at least three good 

 reasons why such differences should exist. 



1. The climate of the Chatham Islands is only suitable 

 for certain portions of the New Zealand flora. It is not 

 suitable for xerophilous or desert-loving types such as 

 Discaria and the New Zealand brooms ( Carmichaelia^ 

 Notospartiuni), nor is it suitable for the alpine and 

 subalpine types which form such a characteristic feature 

 of the New Zealand vegetation. 



2. In the days of " Great New Zealand " the physical 

 condition of the land must have been such as to bring 

 about the existence of an enormous desert tract between 

 the Chathams and New Zealand proper. Even in the 

 New Zealand of the present day the lofty range of the 

 Southern Alps cuts off most of the rainfall from the 

 Canterbury Plains, and this condition of drought must 

 have been greatly aggravated in upper Pliocene times, 

 when the Southern Alps were very much higher than at 

 the present time and the interior of the desert was much 

 further removed from the sea. Thus the more elevated 

 area of the Chathams, though connected indeed with New 

 Zealand, was at the same time in large measure separated 

 by a desert tract which must have formed a very serious 

 barrier to the migration both of plants and animals. A 



