Tr 



738 



KEroRT — 1884. 



\ r\ '■\y\y\fK-'^f^ ' 



Devonian, 



Silurian ? 



l^V/ \J\.' yj ^I'^i \/~\y 



(Unconformable on the Old Cape Schists and 

 Shitcs and on the Bokkoveld Beds.) 

 3. Bokkoveld ]'«ods, 1,100'. 



(Probably unconformable to the Miilmesbury 

 Beds.) 

 2. !Malmcsbury P>eds, ^licascliists and Slatos of the Cape. 



(Probable unconfonnitj-.) 

 1. Namaiiualand Schists and Gneiss. 



Mr. Stows Old Kocki^ of tlie Vaal, and liis Kaap or Camphell-Randt sorit's, in 

 Griqualand-West and tlie Ti-ansvaal, are probably Lower-palajozoic, or even ot 

 greater ago (like Nos. 1 and 2), 



o. On the lYMre Ancient Land Floras of the Old and Xew Worlds. 

 Bij Principal Sir W. Dawson, GM.G., LL.D., F.R.S. 



In the Lanrentian period vogetaMe life is probably indicated, on both .sides of 

 the Atlantic, by the deposits of jjrrapliite found in certain horizons. There is <:ood 

 evidence of the existence of land at the time when these <rraphitic beds -weru 

 deposited, but no direct evidence as yet of land ])lant3. The carbon of these bed.* 

 might have been wholly from sub-aquatic vegetation ; but there is no certainty 

 that it may not have been in part of terrestrial origin, and thei-e are perliaps f^omc 

 chemical arguments in favour of this. The solution of the que.-^tion depends on 

 the possible discovery of unaltered I.aurentian sediments. 



The Silurian land tlora, so far a;- known, is meagre. The fact that Eoptpr)x\n> 

 teen found to be merely a iilm of ])yrite deprives us of ttie ferns. There remain 

 some verticillately-leaved plaTits allied to Annulnria, the humble Aerogcns of tht 

 genus Psi/op/ii/ton, and the somewhat enigmatical plant* of the genera Prir/n/f/iecd, 

 Profofn.rttcs, and Benrijuia, with some uncertain Lycopods. NVi- have thus at 

 least foreruiuiers of the families of the AstcrophijUifccc, the Lijcnpodidvcce, and the 

 ConiferfC. 



The compari.son of the rich Devonian or ICrian flora of the two sides of tin 

 Atlantic is very interesting. C^n both continents it presents three phases, tliost 

 of the Lower, Middle, and Upper Erian, and there is a remarkable correspondence 

 of these in countrit's so Avide apart as Scotland, llelginm, Oiinada, Brazil, anii 

 Australia. lOxamples of this were given in the Iihizocarps, at this period very 

 important, in the Lycopods, the l']quisetacea^, the Ferns, and the Conifers. The 

 number of coniferous trees belonging to Dadtuj/hn and allied genera, and tlie 

 abundance of ferns, often arborescent, were especial features of the iNIiddie and 

 Later Erian. 



The Ihn'a of the Erian age culminated and then diminished. In like manner 

 that of the succeeding Carboniferous period had a small commencement quite dis- 

 tinct in its species from the; Erian; it cuhninated in the ricli vegetation of the 

 true cofJ formation, which Avas remarkably similar over the whole world, present- 

 ing, however, some curious local ditl'erences and dividing lines which are begin- 

 ning to become more manifest as discovery proceeds. In the Upper ( 'arbc niferous 

 the flora diminishes in richness, a!id the Permian age is, so far as kni)wn, one ut 

 dt'cak'uce rather than of new forms. Great progress has recently been made b\ 

 Williamson and others in unravelling the affinities of the coal-formation ])Iant!=, 

 and we are on the eve of important discoveries in this field. 



Tlu'onghout the Silurian, the conditions do not seem to have been eminently 

 favourable to plants, but the few forms Icn own indicate two types of Acrogens, and 

 one leading to the Gyranospenns, and there is no reason to doubt the existence ol 

 insular land richly clothed at least with the few forms of vegetation known to 

 have existed. 



In the lOrian and Carboniferous there seem to have been two great waves of 

 plant-life, proceeding over the continents from the north, and separated by an 

 interval of comparative sterility. But no very material advance was made ni 

 them, so that the flora of the whole Pahcozoic period presents a great unity mul 



