PRESIDENT'S ADDRESS. lix. 



which include the Mosses and Liverworts, the latter differ from 

 the former in the absence of true leaves, and the underside of 

 the plant having a different organisation to the upperside which 

 is exposed to the light. The Pteridophyta have fibre-vascular 

 bundles, and are furnished with a distinct epidermis ; they 

 propagate their species by an alternation of generation, in which 

 the spore on germination produces a new organism, unlike that 

 of the parent, and this can be traced more or less clearly in all 

 vascular plants (Pteridophyta and Phanerogamae). The Filices, 

 Equisetacece and Lycopodiaceas, produce only one kind of spore. 

 On germination the sexual spore produces a small inconspicuous 

 organism, consisting of cellular tissues on which the sexual 

 reproductive organs are borne, and the Oospore thus produced 

 by fertilisation brings out a well developed plant furnished with 

 stem, leaf, and root. The Devonian beds are rich in well 

 characterised Filicidae. There is no satisfactory evidence of any 

 Fern in the Silurian beds, Dawson records more than 30 species 

 from the Devonians of Canada. Pal&opteris occurs in the 

 Upper Devonian and the Lower Carboniferous beds of 

 Europe and North America. Palaopteris hibernica, which 

 has been found in the Devonian beds of Ireland, is one 

 of the most beautiful of the family of Ferns, its large 

 luxuriant fronds bearing broad ovate pinnules. When 

 Brongniart founded his classification of fossil Ferns on 

 their venation, scarcely anything of the fructification was 

 known ; even at the present time our knowledge of the 

 Palaeozoic and Mesozoic forms is very imperfect, for there are 

 many species of which the fructification is unknown, on 

 account of their imperfect state of preservation. To Stur 

 must be given the credit for laying down the principles of a 

 rational classification of fossil Ferns. Those from the Upper 

 Cretaceous and Tertiary beds, appear to be allied to living 

 species. Fern-stems have only been preserved in the form of 

 casts, and consequently possess small interest to the botanist. 

 When the inner structure can be distinguished it is found that 

 it does not differ essentially from that of the living Fern. 



