OF THE INTERIOR OF WESTERN AUSTRALIA. 261 
few cases, as already mentioned, proximity to the rocks is a great 
advantage. Moreorer, it seems impossible, on Professor Tate's 
view, to explain why all the ground near rocks is not dense!y 
clothed with vegetation. One would think that, in a country 
where the rainfall is so small, and where, for all their adapta- 
bility to resist the effects of drought, plants undoubtedly suffer 
during long dry intervals, there would be, as it were, a general 
movement towards places where injury from this cause would be 
reduced to a minimum. This is, however, not the case: indeed, 
the neighbourhood of the rocks is almost always remarkably 
bare, and far more so than the surrounding country. The facts 
are only to be explained on the supposition that the red soil 
contains ingredients which are unsuited to the roek plants, while 
the grauitie soil is not favourable to plants which flourish in red 
soil. 
The prevalence of Myrtaceæ on stretches of pale soil where 
there are no outcropping rocks has already been mentioned. 
Directly one arrives at such a stretch of country, the gum-trees 
drop off and disappear entirely or almost so, and are replaced by 
shrubs, usually Myrtaceous. Singular as it may seem, I do not 
remember to have met with oue of these Myrtaces near a 
gnamma-rock, and the only explanation one can find for this is 
that there is a third kind of soil specially suited to this Myrta- 
ceous vegetation. The change in the flora is often very striking ; 
thus I recall one place, between Coolgardie and Gibraltar, where 
the thickly growing Myrtacee ended quite suddenly and stood 
like a battalion of troops drawn up on parade, and they were 
visible in this order for a long distance. 
To a few species the nature of the soil seems immaterial. I 
have noted Sterculia diversifolia, Pholidia scoparia, Phebalium 
tuberculosum, Sc@vola spinescens, Trichinium obovatum, and 
certain grasses as flourishing near gnamma-rocks and also in red 
soil, without any spe-ial preference for either situation. 
