of Australia.] INTKODUCTORY ESSAY. d 



•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 Palaeozoic rocks of Australia contain fossil plants of which so little, botanically, 

 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 England, and 

 in India ;* Phyllotheca, a plant somewhat similar to Casuarina, but of extremely doubtful affinity ; 

 Vertebraria, also an Indian fossil, as to the affinities of which no plausible guess has been made; 

 Sphenopteris and Zygophyllites, of which little more can be said. To these the Rev. W. B. Clarke+ 

 adds the following well-known British coal fossils, — Lepidodendron, Halonia, Sigillaria, Ulodendron, 

 Calamites, and Stigmaria. 



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 Banksia and Araucaria wood of 

 Tasmania, the Banksia cones of Victoria (which seem identical with those of B. ericifolia, though 

 buried under many feet of trap). The leaves of the calcareous tuffs on the banks of the Derwent,! 

 etc., appear however to belong to a different and warmer period. 



From the above it would appear that the extinct Flora of Australia was not entirely different 

 from that now existing, and, following Mr. Jukes's line of argument, that Australia continued as dry 

 land during the European Oolitic and Cretaceous periods. At this epoch Mr. Jukes assumes that the 

 peculiar Flora of Australia was introduced, and that the continent was again submerged during the 

 Tertiary epoch, when it presented the appearance of two long islands, 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 I 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 ignoranae as to the condition of all the continents during the Palaeozoic epoch, 

 it is impossible to speculate on the earlier condition of the Australian Flora. That previous to some 

 Tertiary submersion of a great part of the continent, it was not altogether specifically different from 

 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 we know to have buried a plant apparently identical with Banksia ericifolia, which is still 

 one of the commonest trees in that part of the country : but the question of where the Banksias 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. f Joum. Geolog. Soc. Lond. vol. iv. p. 60. 



% Darwin's Journal, p. 535, and Volcanic Islands, p. 140 ; Strzelecki, p. 254 ; Milligan in Tasman. Journ. 

 i. 131. 



VOL. I. t 



