of Australia.'] INTRODUCTORY ESSAY. IV 
tained that the western one was modern and derivative; but in DO other part of the world are 
recently-formed lands tenanted exclusively by endemic plants, nor do they present assemblages of 
very local species; on the contrary, they are inhabited by many individuals of a few species derived 
from surrounding countries, of which some few are so altered as to be distinguished as varieties or even 
species ; and we cannot therefore accept the geological evidence as good for explaining the botanical 
phenomena. 
There is another way of viewing the whole question, but one so purely speenlative that I hesi- 
tate to put it forward. It is that the antecedents of the peculiar Australian Flora may have inha- 
bited an area to the westward of the present Australian continent, and that the curious analogies 
which the latter presents with the South African Flora, and which arc so much more conspicuous 
in the south-west quarter, may be connected with such a prior state of things. 
* 7. 
On the Flora of Countries around Spencer's Gulf. 
South Australia, which now ranks as a distinct colony, has been but imperfectly explored. 
and is apparently very poor in species. Some notices of its botany will be found in Lmdley I tnd 
Hooker's Appendices to Mitchell's Journeys; in Brown's 'Appendix to Sturt's Journey ;' m Hooker I 
* Kcw Miscellany,' 1863, p. 105 } and, more recently, in Mueller's Report on the plants collected by 
Mr. D. Hcrgolt during Babbagc's expedition. They all show that the character of the Flora is 
intermediate between the south-eastern, south-western, and tropical Floras, the eastern being perhaps 
the dominant, and the tropical due to the proximity of the central desert. 
Amongst the western genera and species which here approach their eastern limits arc Hibiscus 
hakeafolius and multifidus, Cyanothamuus, Softya heterophylla. Cheiranthera, Bosshra sulcata, Tem- 
pletonia retusa, Clianthus Dampieri, Xifraria BiUardieri, Adenanthera terminalis, Podotheca, Cy/in- 
drosorus flavescem, Loc/ania crassifolia, Anthocercis anisantha, Cyclotheca aiistralica, and Codono- 
carpus urue'upformis ? 
The tropical element is displayed by species of Crot a/aria, Polycarpaa, Mown teles, Pluchea, 
Glossogyne, Sarcostemma, Trichodesma, Rostellularia, and Santalum. Mueller further alludes to a 
succulent, leafless Euphorbia, probably of the Indian or South African type. The absence or rarity 
of Proteacea, Sophorea?, Myrtaeeee, Diosmere and Epacridea, and prevalence of Composite, Ere.no- 
phila, Zyyophyllece and Salsolea, are other proofs of the tropical and desert character of the South 
Australian Flora. 
From the examination of a considerable collection of South Australian species made by Messrs. 
Whitakcr, Dutton, Hillebrandt, etc., I am inclined to suspect that it contains so few peculiar genera, 
re either identical with or strictlv intermediate in character 
and so large a numb'-r of >p«vie- which arc either identical with o 
between eastern and western ones, or which are so closely allied to congeners of 
that they will favour the idea of the Flora being to a very great extent derivative. 
