CIV FLORA OF TASMANIA. fossil Plants, Geology, etc., 
Madras peninsula, except the western coast and mountains, the valley of the Irrawaddi, and the lower 
flat districts of the Malay Islands, whence it is continued in great force over the whole of tropical 
Australia. 
Reversing the position, and beginning at the southern extreme of this arc of vegetation, there is 
first the Antarctic Flora (the complement of the Scandinavian), with its decided Australian represen- 
tatives in Centrolepidece and Stylidiece, commencing in Fuegia, the Falklands, and Lord Auckland's and 
Campbell's group, reappearing in the alps of New Zealand, Tasmania, and Australia, and disappearing 
under the equator, on the alps of Borneo, being thus strictly confined to the southern hemisphere. 
Next there is the Australian Flora proper, a large and highly developed one, diminishing rapidly after 
crossing the southern tropic, and as it advances towards the north-western shore of the continent, 
reappearing in very small numbers in the Malay Islands, and terminated by a Casuarina on the east 
coast of the Bay of Bengal, and a Stylidium on the west. Not one representative of this vegetation 
advances further north-west. 
Analogous appearances are presented by Africa and America. In Africa Indian forms prevail 
throughout the tropics, and, passing southwards, occupy the northern boundary of the south tempe- 
rate zone ; but there a very copious and widely different vegetation succeeds, of which but few repre- 
sentatives advance north to the tropic, and none to India, but with which are mingled Scandinavian 
genera and even species. In the New World, Arctic, Scandinavian, and North American genera and 
species are continuously extended from the north to the south temperate and even Antarctic zones ; 
but scarcely one Antarctic species, or even* genus {Forstera, Calceolaria, Colobanthus, Gunnera, etc. 
etc.) advances north beyond the Gulf of Mexico. 
These considerations quite preclude my entertaining the idea that the Southern and Northern 
Floras have had common origin within comparatively modern geological epochs j on the contrary, 
the European and Australian Floras seem to me to be essentially distinct, and not united by those 
of intervening countries, though fragments of the former are associated with the latter in the southern 
hemisphere. For instance, I regard the Indian plants in Australia to be as foreign to it, botanically, 
as the Scandinavian, and more so than the Antarctic ; and that to whatever lengths the theory of varia- 
tion may be carried, we cannot by it speculate on the Southern Flora being directly a derivative one 
from the existing Northern. On the contrary, the many bonds of affinity between the three southern 
Floras, the Antarctic, Australian, and South African, indicate that these may all have been members 
of one great vegetation, which may once have covered as large a southern area as the European now 
does a Northern. It is true that at some anterior time these two Floras may have had a common 
origin, but the period of their divergence antedates the creation of the principal existing generic 
forms of each. To what portion of the globe the maximum development of this Southern Flora 
is to be assigned, it is vain at present to speculate; but the geographical changes that have re- 
sulted in its dismemberment into isolated groups scattered over the Southern Ocean, must have 
been great indeed. Circumscribed as these Floras are, and encroached upon everywhere by northern 
forms, their ultimate destiny must depend on that power of appropriation in the strife for place which 
we see in the force with which an intrusive foreign weed establishes itself in our already fully peopled 
fields and meadows, and of the real nature of which power no conception has been formed by natu- 
ralists, and which has not even a name in the language of biology. Everywhere, however, we see the 
more widely distributed, and therefore least peculiar forms of plants, spreading, and the most pecu- 
liar dying out in small areas, and the progress of civilization has introduced in man a new enemy to 
a. See p. xc. in note. 
