2 INTRODUCTION 



Gwynne-V aughani, the first example of the Psilophy ton flora to 

 be known in the petrified state. The importance of this beautifully 

 illustrated memoir can hardly be exaggerated. As we hope to 

 show, it offers us the key to the chief mysteries which have 

 hitherto surrounded the question of the affinities of this type of 

 land vegetation. 



Next we have a series of important memoirs by Nathorst x and 

 Halle 2 on Lower and Middle Devonian floras from Norway. 

 There is, further, the interesting paper by Don and Hickling 3 

 on the British Lower Devonian land plant, Parka decipiens. 



With these recent contributions we may associate others, 

 published earlier, especially the works on Upper Devonian floras 

 by Nathorst 4 from Bear Island and Ellesmereland, by David 

 White 5 from the United States, and last but not least, the very 

 interesting Middle Devonian flora of Bohemia 6 . 



1 Nathorst (1913), (1915). 2 Halle (1916). 



3 Don and Hickling (1917). 4 Nathorst (1902), (1904). 



5 White (1905), (1907). 6 Potonie and Bernard (1904). 



