1899] ORIGIN OF AUSTRALIAN FLORA 211 
in which, for instance, Galinsoga parviflora, and species of Aster are 
enabled to maintain themselves in Europe, any inherent superiority of 
the American flora over the European? Yet argument of this kind we 
find constantly applied to the flora of Australia. Nor is present dis- 
tribution an infallible index to the place of origin of a genus or 
species. To take two instances showing the general trend of argument 
on this subject as bearing on the flora of Australia: Helichysum and 
Helipterum, although well represented in Australia, are found also in 
other countries ; consequently, it is said, they are exotic genera which 
have at some time migrated into Australia. Why may not they, as 
well as other genera, be descendants from the constituents of the 
“primitive tertiary flora”? Professor Tate partially adopts this view, 
for he remarks, apropos of certain genera found fossil in tertiary 
deposits, such as Ficus, Loranthus, Pittosporum, Santalum, and Cassia— 
that most of these genera, “ when viewed by their present geographical 
distribution, are considered Oriental; but in regard to their distribution 
in time they belong to a cosmopolitan flora, which originated in late 
Cretaceous times in Europe, North America, and Australia ; hence their 
modern representatives may actually be descendants of primitive 
Australian species, and not modified immigrant forms.”’ But though 
he makes this highly important admission, in practice he adopts the 
conventional view, for we find him distinguishing “immigrant ” genera 
and species from “endemic” ones with confidence as serene as though 
he had himself been privileged to watch, through long ages, all the 
various steps in the stocking of Australia. Of course the view I am 
advocating cuts both ways. The Cambodian Centrolepis, for instance, 
may possibly be the sole Indo-Malayan survivor of a genus which had 
its origin in the Indo-Malayan region, and migrated thence into 
Australia. So too Patersonia may be of Indo-Malayan origin: even 
Casuarina equisetifolia may be, for all we know, the original species 
from which its Australian congeners have been derived. Not until all 
later secondary and tertiary deposits have been thoroughly ransacked, 
and their respective relations in time established beyond dispute, will 
it be possible to fix upon that part of the earth where a genus ora 
species first made its appearance. Until this is accomplished our con- 
clusions can rest on nothing more satisfactory than inferences from 
present distribution, which, unless they be applied with the utmost 
caution, may lead us far from the truth. 
The most recent and, as having been deduced with full knowledge 
of modern geological discoveries and after perscnal inspection of part 
of the country, the most authoritative conclusions relative to the origin 
of the Australian flora are those of Professor Tate.” The Darling 
1 “Botany of the Horn Expedition,” p. 131. 
* Professor Tate’s three memoirs, The Influence of Physiographic Changes in the Dis- 
tribution of Life in Australia; Australia’s Association for the Advancement of Science 
(1887) ; Inaugural Address, in the Association’s volume for 1893, and the “ Botany of the 
Horn Expedition ” (1896), are most interesting contributions to the subject under notice. 
