1 FLORA OF TASMANIA. [Extra-tropical Flora. 



fifth. The number of arboreous and shrubby plants is very considerable, showing that this portion of 

 the Flora is not wholly made up of transported weeds. 



Lastly, I have to allude to the remarkable absence of any reciprocity between the vegetation of 

 Australia and India, for though I have given nearly 500 Indian species, and upwards of 200 genera, 

 that are very decidedly Indian types of vegetation, I am not aware of a single Australian species in 

 central India or in the "western Indian peninsula, or one Australian genus that is common there. 

 The only Australian genera that are found in any part of India proper are Siylidium (of which a very 

 few species are found in the eastern Peninsula, and one in eastern Bengal, Ceylon, and the country 

 near Calcutta), Lagenophora and Haloragis, which are temperate forms, and the following, which are 

 confined in India to the Malayan Peninsula, or the country immediately adjoining it. 



Philydrum. Casuarina. Tristania. Metrosideros. 



Dacrydium. Leucopogon. Leptospermum. 



To the eastward of India again Bceckia attains the latitude of southern China and the Philip- 

 pines. Microtis vara inhabits New Zealand, Java, and Bonin ; Thelymitra is also Javanese ; a species 

 of Stackhousia is found in the Philippines ; one of the Indian Stylidiums inhabits Hongkong, and 

 Carex littorea (an extra-tropical plant) is a native of Japan. 



According to the hitherto prevailing theory of the distribution of plants, this presence of so 

 many Indian species in tropical Austi-alia would be accounted for by trans-oceanic migration, but this 

 theory offers no explanation of the total absence of Australian species and typical genera in the 

 tropical parts of India. Eucalyptus, Acacia, Stylidium, and Goodeniacece, are characteristic of tropical 

 as well as of temperate Australia, together with various peculiar genera of Leguminosa, Compositm, 

 Myrtacece, Myoporinece, Logaaiacem, Restiacece, Conifera, and Orchidece, which are not represented in 

 tropical India. 



Some of these genera {Acacia, Eucalyptus, and Casuarina) flourish when planted in the Penin- 

 sula of India, and it would be interesting to know whether they become naturalized, for it appears 

 to me to be difficult to conceive that there should be anything in the condition of the soil, vegetation, 

 or climate of India that would wholly oppose the establishment of Australian plants, had they been 

 transported thither by natural causes now in operation ; and I cannot suppose that there should 

 have been no migration from Australia to India if there was such a migration in the opposite direc- 

 tion as would account for so great a community of vegetation between these continents. 



* 6. 



On the Flora of Extra-tropical Australia. 



In studying the extra-tropical Flora of Australia, the first phenomenon that attracts attention is 

 the remarkable difference between the eastern and western quarters, to which there is nothing analo- 

 gous in the tropical region. "What differences there are between eastern and western tropical Aus- 

 tralia are confined to more Asiatic forms in the latter, and more Polynesian and temperate Australian 

 ones in the former ; this is analogous to that preponderance, to which I shall hereafter allude, of 

 the South African types in south-western Australia, and of New Zealand and Antarctic ones in 

 south-eastern ; but offers nothing analogous to the fact that the species, and in a great extent the 

 genera, of south-western Australia differ from those of south-eastern, though these species and 



