of Australia.'] INTRODUCTORY ESSAY. lv 



tained that the western one was modern and derivative ; but in no 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 cqntrary, 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 speculative 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 are 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 Liudley's and 

 Hooker's Appendices to Mitchell's Journeys ; in Brown's ' Appendix to Sturt's Journey f in Hooker's 

 ' Kew Miscellany,' 1853, p. 105 ; and, more recently, in Mueller's Report on the plants collected by 

 Mr. D. Hergolt during Babbage'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 clue to the proximity of the central desert. 



Amongst the western genera and species which here approach their eastern limits are Hibiscus 

 hakeeefolius arid multifidus , Cyanothammts, Solly a heterophylla, Cheirantheru, Bossiaa sulcata, Tem- 

 pletonia retusa, Clianthus Dampieri, Nitraria Billardieri, Adenanthera terminalis, Podotheca, Cylin- 

 drosorus flavescens, Logania crassifolia, Anthocercis anisantha, Cyclotheca auslralica, and Codono- 

 carpus acaciceformis ? 



The tropical element is displayed by species of Crotalaria, Polycarpcea, Monenteles, Plucheu, 

 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 Proteacece, Sophoreee, Myriacem, Diosmece and Epacridece, and prevalence of Composite, Eremo- 

 phila, Zygophyllees and Salsolete, 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. 

 Whitaker, Dutton, Hillebrandt, etc., I am inclined to suspect that it contains so few peculiar genera, 

 and so large a number of species which are either identical with or strictly intermediate in character 

 between eastern and western ones, or which are so closely allied to congeners of one or the other, 

 that they will favour the idea of the Flora being to a very great extent derivative. 



