INTRODUCTOKY ESSAY. XIX 



evidence in the fact that, in the meridians of Australia and Japan, we have, first, the north-west 

 coast of Australia sinking, together with the Louisiade Archipelago to its north ; then, approaching 

 the Line, the New Ireland group is sinking, as are also the Caroline Islands, in lat. 7° N. Beyond 

 this, however, in lat. 15° N., are the Marianne Islands (rising), of whose vegetation nothing is 

 known ; in 27° N., the Bonin Islands (also rising) ; and in 30° N. is Japan, with which this bota- 

 nical relationship exists. 



It is objected by Mr. Darwin to this line of argument (as to that at p. xv concerning the 

 Pacific Islands), that all these sinking areas are volcanic islands, having no traces of older rocks on 

 them ; but I do not see that this altogether invalidates the hypothesis, for many of the loftiest moun- 

 tains throughout the Malayan Archipelago, New Zealand, and the Pacific Islands, are volcanic ; some 

 are active, and many attain 10-14,000 feet in elevation, whilst the lower portions of some of the 

 of these islands are formed of rocks of various ages. 



On the General Phenomena of the Distribution of Plants in Time. 



A third class of facts relates to the antiquity of vegetable forms and types on the globe, as evi- 

 denced by fossil plants. The chief facts relating to these are the following : — 



31. The earliest Flora of which we know much scientifically, is that of the Carboniferous forma- 

 tion. We have indeed plants that belonged to an earlier vegetation, but they do not differ in any 

 important respects from those of the carboniferous formation. 



Now the ascertained features of the coal vegetation may be summed up very briefly. There 

 existed at that time, — 



Filices ; in the main entirely resembling their modern representatives, and some of which may 

 even be generically, though not specifically, identical with them. 



Lycopodiacece ; the same in their main characters as those now existing, and, though of higher 

 BpeciaEiSiSsm of stem, of greater stature, of different species, and perhaps also genera, from modern 

 Lycopodiacece, yet identical with these in the structure of their reproductive organs and their con- 

 tents, and in the minute anatomy of their tissues. 



Coniferee. The evidence of this Order is derived chiefly from the anatomical characters of the 

 Dicotyledonous wood so abundantly found in the coal, and which seems to be identical in all impor- 

 tant respects with the wood of modern genera of that Order, to which must be added the probability 

 of Trigonocarpon and Naggerathia being Gymnospermous, and allied to Salisburia* On the other 

 hand, it must not be overlooked that no Coniferous strobili have been hitherto detected in the Car- 

 boniferous formation. 



Cycadeee. Some fragments of wood, presenting a striking similarity in anatomical characters 

 to that of Cycadeee, have been found in the carboniferous series. 



In the absence of the fructification of Catamites, Calamodendron, Halonia, Anabafhra, etc., 

 there are no materials for any safe conclusions as to their immediate affinities, beyond that they all 

 seem to be allied to Ferns or Lycopodiacece ; but the same can hardly be said of the affinities ot 

 Volkmannia,i Antholith.es and others, which have been referred, with more or less probability, to 

 Angiospermous Dicotyledons. 



The Permian Flora is for the most part specifically distinct from the Carboniferous, but many of 

 * Phil. Trans. 1855, p. 149. f See Quarterly Journal of Geological Society, May, 1854. 



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