494 



ISLAND LIFE 



PAET II 



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 

 Joseph Hooker remarks : — " What differences there are 

 in conditions would, judging from analogy with other 

 countries, favour the idea that South-eastern Australia, 

 from its far greater area, many large rivers, extensive 

 tracts of mountainous country and humid forests, would 

 present much the most extensive flora, of which only the 

 drier types could extend into South-western Australia. 

 But such is not the case ; for though the far greater area is 

 much the best explored, presents more varied conditions, 

 and is tenanted by a larger number of Natural Orders and 

 genera, these contain fewer species by several hundreds."^ 



The fewer genera of South-western Australia are due 

 almost wholly to the absence of the numerous European, 

 Antarctic, and South- American types found in the south- 

 eastern region, while in purely Australian types it is far 

 the richer, for while it contains most of those found in the 

 east it has a large number altogether peculiar to it ; and 

 Sir Joseph Hooker states that " there are about 180 

 genera, out of 600 in South-western Australia, that are 

 either not found at all in South-eastern, or that are 

 represented there by a very few species only, and these 

 180 genera include nearly 1,100 species." 



Geological Explanation of the Differences of these Two 

 Floras. — These facts again clearly point to the conclusion 

 that South-western Australia is the remnant of the more 



1 Sir Joseph Hooker thinks that later discoveries in the Australian Alps 

 and other parts of East and South Australia may have greatly modified or 

 perhaps reversed the above estimate, and the figures given in the preced- 

 ing note indicate that this is so. But still, the small area of South-west 

 Australia will be, proportionally, far the richer of the two. It is much to 

 be desired that the enormous mass of facts contained in Mr. Bentham's 

 Flora Australiensis and Baron von Miieller's Census should be tabulated 

 and compared by some competent botanist, so as to exhibit the various 

 relations of its wonderful vegetation in the same manner as was done by 

 Sir Joseph Hooker with the materials available twenty-one years ago. 



