CHAP. XXII THE FLORA OF XEW ZEALAND 493 



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 trojDical Australia is, comparatively, recent 

 and derivative. If we imagine the greater part of North 

 Australia to have been submerged beneath the ocean, from 

 Avhich 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 j^resent condition of things w^ould 

 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 adaj^ted 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 wdiat was required, 

 in order to bring about the wonderful amount of special- 

 isation and the high develoiDment 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. 



Tlir Floras of Soitth-eastcrn and Soutli-vjestcrn Australia. 

 — The peculiarities presented by the south-eastern and 

 south-western subdivisions of the flora of temperate 

 Australia are most interesting and suggestive, and are, 

 perhaps, unparalleled in any other part of the world. 

 South-west Australia is far less extensive than the south- 

 eastern division — less varied in soil and climate, with no 

 lofty mountains, and much sandy desert ; yet, strange to 

 say, it contains an equally rich flora and a far greater 

 proportion of peculiar species and genera of plants. As Sir 



