ANNIVERSARY ADDRESS OF THE PRESIDENT. IO5 



most abundant types throughout the globe. A little later in the 

 geological sequence, in the Eocene, there is a similar advent of 

 placental Mammals, anurous Batrachia, Ophidia, and perhaps of 

 modern types of Lacertilia. The origin of the placental Mammalia 

 was discussed twenty years ago by Professor Huxley, in one of the 

 most interesting and suggestive addresses ever delivered from this 

 Chair, and the conclusion to which he came affords the only satis- 

 factory explanation hitherto offered. He showed that the subclass 

 had in all probability been developed for ages before the Eocene 

 period in an isolated continental area that has now apparently 

 disappeared, but which he suggested may have been in the Pacific. 



I am inclined to believe that the origin of Dicotyledonous Angio- 

 sperms is even a more remarkable case than that of placental 

 Mammals. There is much evidence in favour of the process of modi- 

 fication and evolution amongst plants being far slower than in the 

 higher animals, and many of the Cretaceous and Eocene Angio- 

 spermous genera are undistinguishable from those existing at the 

 present day. This Angiospermous flora could only have originated in 

 a great tract of land, and unless that tract was isolated by ocean 

 from all countries in which the earlier Mesozoic flora of Cycads, 

 Conifers, Equisetaceae, Perns, &c., has been found, it is difficult to 

 understand why no traces of the ancestral Angiospermous forms 

 have been detected amongst the latter. 



The Mesozoic flora itself appeared in a considerable portion of the 

 northern hemisphere in the Triassic period as suddenly as the 

 Angiospermous flora did in the Cretaceous. But in this case 

 we have a clue to the origin of the invaders ; for we now know 

 that this Mesozoic flora came from the south, and had established 

 itself in Australia, India, and in South Africa at an Upper Palaeo- 

 zoic epoch, whilst the well-known Palaeozoic flora of gigantic 

 Lycopodiacece and peculiar Equisetaceoe and Perns still flourished in 

 Europe, Northern Asia, and North America. There is, moreover, 

 some evidence in favour of the view that the transfer of the southern 

 plants to the northern hemisphere was caused by a period of low 

 temperature that drove a southern temperate flora northward to the 

 equator. It is known from the scanty remnants of an older Carbo- 

 niferous (or Upper Devonian) flora found in Australia that Lycopo- 

 diaceous plants, similar to northern Palaeozoic forms, occurred in 

 the southern area at an earlier date, and it is quite possible 

 that the Newcastle flora of Australia and the Gondwana flora of 

 India, the evident precursors of the Mesozoic flora of Arctogaea, 



