of Australia.} INTRODUCTORY ESSAY. CI 
Araucaria of the English oolite, and other fossils alluded to at p. xxi., would seem to tend to confirm 
Mr. Jukes's observation. 
The so-called Paheozoic rocks of Australia contain fossil plants of which so little, hotanically. 
is known, that it would be rash to speculate on their affinities, even if we knew the age of the beds 
they are found in, as compared with the European, which we do not. Their fossils comprise Ferns of 
several genera, including the genus Glossopteris, which is found in the oolitic beds of Kngland, and 
in India;* Phyllotheca, a plant somewhat similar to Casuarina, but of extremely doubtful aflinity ; 
Vertebrarkt, also an Indian fossil, as to the affinities of which no plausible guess has been made; 
Sphenopteris and ZijgophyUites, of which little more can be said. To these the Rev. \V. Is. (larket 
adds the following well-known British coal fossils,— Lepidodendron, Halonia, Sh/il/aria, llothndnm, 
Calaiiiites, and Sfiamaria. 
Many of the tertiary fossil plants of Australia would seem to be very closely allied to existing 
ones; these include the Casuarina cones of Flinders Island, the Banktia and Aruiiraria wood of 
Tasmania, the Banksia cones of Victoria (which teem identical with those of />'. rririfo/ia, though 
buried under many feet of trap). The leaves of the calcareous tuffs on the bankl of the Dcrwent,! 
etc., appear however to belong to a different and wanner period. 
From the above it would appear that the extinct Flora of Australia was not cnthely different 
from that now existing, and, following Mr. Jukes's line of argument, that Australia continued as dry 
land during the European Oolitic and Cretaceoni periods. At thi> epoch Mr. Jukes assumes that the 
peculiar Flora of Australia was introduced, and that the continent was again inbmerged during the 
Tertiary epoch, when it presented the appearance of two long island-, or chains of islands, one, the 
larger, representing the elevated land of eastern Australia and Tasmania, the other that of south- 
eastern Australia, together with subsidiary groups in the western and northern parts of the continent. 
These are the speculations of an able geologist and voyager, which 1 introduce without com- 
ment, and chiefly to observe that such a partition of the continent may be supposed to be favourable 
to the multiplication of forms of vegetable life out of fewer pre-existing ones, by the segregation of 
varieties. These groups of islands would present a precise analogy with the Galapagos and Sand- 
wich groups, where we have the small islands of one Archipelago peopled by different species, and 
even genera. The subsequent elevation of these islets, and consequent union of them into larger 
ones, would further, according to Darwin's hypothesis (of the struggle of very different kinds of 
species and families for occupation of the soil resulting in a further separation of varieties into 
species), tend to enlarge the genera numerically within comparatively small geographical limits, and 
thus effect such a geographical distribution of plants as Australia now presents. 
In our complete ignorance as to the condition of all the continent! during the Paheozoic epoch, 
it is impossible to speculate on the earlier condition of the Australian flora. That i > 
Tertiary submersion of a great part of the continent, it was not altogether speciiicalh 
what it now is, would appear from a fact insisted on by Mr. Jukes, that it was during such a submer- 
sion that those volcanos were active, the lavas of which now cover large tracts of southern Australia, 
and which wc know to have buried a plant apparently id. ntieal with linnkxia vririfuHa, which is still 
one of the commonest trees in that part of the country : bat the question of where the Banhsias and 
their allies were created, and, if in other lands than Australia, how they migrated thither, we have no 
* M : Coy in Ann. Nat. Hist. vol. xx. p. 152. | Journ. Geolog. Soc. Lond. vol. iv. p. 60. 
% Darwin's Journal, p. 535, and Volcanic Islands, p. 140 ; Strzelecki, p. 254 ; Milligan in Tasman. Journ. 
