CHAP. XXII THE FLORA OF NEW ZEALAND 493 



identical with Indian or Malayan plants, or are very close 

 representatives of them ; while there are more than 200 

 Indian genera, confined for the most part to the tropical 

 portion of Australia. The remainder of the tropical flora 

 consists of a few species and many genera of temperate 

 Australia which range over the whole continent, but these 

 form only a small portion of the peculiarly Australian genera. 



These remarkable facts clearly point to one conclusion — 

 that the flora of tropical Australia is, comparatively, recent 

 and derivative. If we imagine the greater part of North 

 Australia to have been submerged beneath the ocean, from 

 which it rose in the middle or latter part of the Tertiary 

 period, offering an extensive area ready to be covered by 

 such suitable forms of vegetation as could first reach it, 

 something like the present condition of things would 

 inevitably arise. From the north, widespread Indian and 

 Malay plants would quickly enter, while from the south 

 the most dominant forms of warm-temperate Australia, and 

 such as were best adapted to the tropical climate and arid 

 soil, would intermingle with them. Even if numerous 

 islands had occupied the area of Northern Australia for 

 long periods anterior to the final elevation, very much the 

 same state of things would result. 



The existence in North and North-east Australia 

 of enormous areas covered with Cretaceous and 

 other Secondary deposits, as well as extensive Tertiary 

 formations, lends support to the view, that during very 

 long epochs temperate Australia was cut off from all close 

 connection with the tropical and northern lands by a wide 

 extent of sea ; and this isolation is exactly what was required, 

 in order to bring about the wonderful amount of special- 

 isation and the high development manifested by the 

 typical Australian flora. Before proceeding further, how- 

 ever, let us examine this flora itself, so far as regards its 

 component parts and probable past history. 



The Floras of Soutk-eastern and South-western Australia, 

 — The peculiarities presented by the south-eastern and 



suppose there can be little doubt that the tropical areas are far the richest. 

 Temperate South Africa is, no doubt, always quoted as richer than an 

 equal area of tropical Africa or perhaps than any part of the world of equal 

 extent, but this is admitted to be aij exceptional case. 



