part 2] ANNIVERSARY ADDRESS OF THE PRESIDENT, XCvii 



pair of sporangia, but of their structure we know nothing. I take 

 this opportunity of thanking him for giving me information about 

 the specimens and their geological age. 



It is clear that in some parts of the world there existed 

 arborescent Lycopodiaceous plants comparable in some respects to 

 the much smaller Rhynia, Hornea, and Psilophyton. We may go 

 farther, and express agreement with Dr. Halle's view that between 

 the older Devonian Psilophy tales and the widespread Upper 

 Devonian Cyclostigma there is a very close alliance. It is, I 

 venture to think, probable that in the swollen bases of the Naples 

 and Gilboa trees we have a feature connected by descent with the 

 tuberous rhizome of Hornea, and on the other hand with the 

 Stigmarian ' roots ' of Sigillaria and JLepidodendron. It is note- 

 worthy that anatomically Stigmaria differs from the erect Sigil- 

 larian or Lepidodendroid stems in the absence of the characteristic 

 cylinder or solid strand of primary vascular tissue : may this 

 difference be interpreted as a consequence of the developmental 

 history of Stigmaria ? The tuberous rhizome of Hornea has no 

 vascular supply of its own : when it increased in size, and a vascular 

 system became essential, the need may have been met by the 

 production of a cylinder mainly composed of secondary conducting 

 tissue. 



Many remains of Lepidodendroid plants have been recorded from 

 the Southern Hemisphere. In the Falkland Islands Dr. Halle, 

 and subsequently Dr. H. A. Baker, found fragments of stems, 

 superficially at least very similar to some specimens of Arthrostigma 

 from Norway and of Protolepidodendron from Bohemia, as also 

 to the later Cyclostigmas : the beds are probably either Lower or 

 Middle Devonian. Many examples of Lepidodendroid remains 

 have been described from the Witteberg Series of South Africa, and 

 recently M. P. F. Mathieu generously sent to me similar specimens 

 from the Belgian Congo. Others have been recorded from Upper 

 Devonian and Lower Carboniferous rocks in Australia. The con- 

 clusion is that, during the Devonian Period, the Lycopod phylum 

 was in vigorous development, and its representatives were 

 geographically widespread. In the size of the individuals, and in 

 the range of form and structure, this phykirn reached its maximum 

 during the latter part of the Carboniferous Period. 



Reference maybe made here to a characteristic Middle Devonian 

 vol. lxxix. g 



