116 THE EVOLUTION OF PLANTS 



even more important point is that the seeds have 

 proved to be altogether of a Cycadean type, as 

 shown by the most careful and detailed investi- 

 gations, carried out by the earlier fossil botanists 

 before the relation of the seeds to the so-called 

 Ferns was known, and by Prof. F. W. Oliver and 

 his colleagues since that discovery. 



We are thus confronted with a great class of 

 Palaeozoic plants which combined, in the most 

 striking way, the characters of Ferns and Cycads. 

 We know that in the succeeding age Cycads, of 

 varied and highly developed types, overspread 

 the whole world. It seems clear that in the Pter- 

 idosperms we have traced them to their source 

 or at least have carried the history of their de- 

 scent a long stage further back. So far as any 

 evolutionary conclusions from the still imper- 

 fect palaeontological record are justified, we are 

 warranted in the belief that the Pteridosperms 

 represent the Palaeozoic stage of evolution of the 

 Cycadophyta and indicate, much more evidently 

 than the Cycads themselves, that the whole of 

 this great race of plants sprang ultimately from 

 a common stock with the Ferns. 



The study of evolution in the light of the Fossil 

 Record thus shows us, what we could never have 

 learnt from the living Flora alone, the extreme 

 importance of the Cycadean stock. Represented 

 now by a small and isolated family, the Cyca- 



