1 FLORA OF TASMANIA. [Extra-lropical 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 Stylidium (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. Metrosideroa. 
Dacrydium. Leucopogon. Leptospermum. 
To the eastward of India again Bceckia attains the latitude of southern China and the Philip- 
pines. Microtis rara inhabits New Zealand, Java, and Bonin j Thehjmitra is also Javanese j a species 
of Stackhousia is found in the Philippines j one of the Indian Stylidiums inhabits Hongkong, and 
Career 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 Australia 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 Goodeniacea, are characteristic of tropical 
as well as of temperate Australia, together with various peculiar genera of Leguminosa, Composite, 
Myrtacea, Myoporinem, Loganiacem, Restiacea, Conifer®, and Orchidea, which arc not represented in 
tropical India, 
Some of these genera (Acacia, Eucalyptus, and Casuarina) nourish when planted in tho 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 c 
$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 
