XX FLORA OF TASMANIA. 



its genera are the same. The prevalent types are Gymnospermous Dicotyledons, especially Cycadece, 

 and a great abundance of Tree-ferns. 



The New Red Sandstone, or Trias group, presents plants more analogous to those of the Oolite 

 than to those of the Carboniferous epoch, but they have also much in common -with the latter. 

 Voltzia, a remarkable genus of Conifers, appears to be peculiar to this period. 



In the Lias numerous species of Cycadece have been found, with various Conifers and many 

 Ferns. No other Dicotyledonous or any Monocotyledonous plants have as yet been discovered, but 

 it is difficult to believe that none such should have existed at a period when wood-boring and herb- 

 devouring insects, belonging to modern genera, were extremely abundant, as has been proved by the 

 researches of Mr. Brodie and Mr. Westwood* 



The Oolite contains numerous Cycadece, Co?iiferce, and Ferns, and more herbivorous genera of 

 insects; and here Monocotyledonous vegetables are recognizable in Podocarya and other Pandaneous 

 plants. A cone of Pinus has been discovered in the Purbeck, and one of Araucaria in the inferior 

 Oolite of Somersetshire. 



In the Cretaceous group, Dicotyledons of a very high type appear. A good many species are enu- 

 merated-)- by Dr. Debey, of Aix-la-Chapelle, including a species of Juglans, a genus belonging to an 

 Order of highly- developed floral structure and complex affinities. { 



Characece appear for the first time at this epoch, and are apparently wholly similar in structure 

 to those of the present day. 



The Tertiary strata present large assemblages of plants of so many existing Genera and Orders, 

 that it can hardly be doubted but that even the earliest Flora of that period was almost as complex 

 and varied as that of our own. In the lowest Eocene beds are found Anmiacece, Nipa, Acacia, and 

 CucurbitacetB.§ In the Bagshot sands some silicified wood has been found, which may confidently 

 be referred to Banksia, and which is, in fact, scarcely distinguishable from recent and fossil Aus- 

 tralian Banksia wood.|| 



* These insects include species of the existing common European genera, Elater, G-ryllus, Eeme^k^Ppke- 

 mera, Libelhda, Panorpa, and Caralus. Of all conspicuous tribes of plants the Cycadece, Filices, Coniferce, and 

 Lycopodiacece perhaps support the fewest insects, and the association of the above-named insects with a vegetation 

 consisting solely or mainly of plants of these Orders is quite inconceivable. 



f Quart. Journ. Geol. Soc. vii. pt. 1. misc. p. 110. 



% Professor Oswald Heer, of Zurich, in an interesting little paper (Quelques Mots sur les Noyers), in Bibl. 

 Univ. Genev. Sep. 1858, argues from the fact of the early appearance of Juglans in the geological series, that this 

 genus must be a low type of the Dicotyledonous class to which it belongs. The position of Juglans is unsettled in 

 the present state of our classification of Dicotyledonous Orders, as it has equal claims to be ranked with Terebintliacece, 

 which are very high in the scries, and with Cnptdifera, which are placed very low; and were the grounds for our 

 thus ranking these Orders based on characters of ascertained relative value, such an argument might be admis- 

 sible ; but the system which sunders these Orders is a purely artificial one, and Juglans with its allies would prove 

 it so, if other proofs were wanting ; for it absolutely combines Terebintliacece and Cupuliferce into one natural group, 

 iu which (as in so many others) there is a gradual passage from great complexity of floral organs to great simplicity. 



§ I am far from considering the identification of these and the other genera which I have enumerated in various 

 strata as satisfactory, but I conclude that they may be taken as evidence of as highly developed and varied plants 

 having then existed as are now represented by these genera. 



|| I am indebted to the late Robert Brown for this fact, and for the means of comparing the specimens, which 

 are beautifully opalized. I ascertained that he was satisfied with the evidence of this wood having really been dug 

 up near Staines, though it is so perfectly similar in every respect to the opalized Banksia-wood of Tasmania as to 

 suggest to his mind and my own the most serious doubts as to its English origin. 



