58 



THE ARCHAEOPTERIS FLORA 



[CH. 



writer '^ some years ago. The large wedge-shaped leaves are in 

 most cases detached, except in specimens from the Middle 

 Devonian of Western Norway, and much younger examples from 

 the Coal Measures of the Newcastle coal field, England, and the 

 Permo-carboniferous of South Africa, where they are borne 

 spirally on a shoot. The Devonian and the British (Carboniferous) 

 examples agree remarkably in habit in this respect. 



Although several species of the genus are known, we remain 

 entirely unacquainted with the fructification. 



Fig. 30. Archaeopteris flmbriata, Nath., from the 

 Upper Devonian of Bear Island, (f nat. size.) 

 After Nathorst (1902). 



It has been thought probable that Psygmophylluni belongs to 



a distinct group of plants, for which the name Palaeophyllales 



was suggested by the writer some years ago. Whether this view 



will prove to be correct or not, depends primarily on the nature 



of the unknown fructification. Until this has been discovered it 



is probably wiser to assume that it represents a distinct type 



than to include it with any other Palaeozoic genus, for among 



such plants the habit of Psygmophyllum is quite unique. 



1 Arber (1912). To complete the Usts contained in this monograph the 

 figures of Platyphyllum Brownianum of D. White (1905), of P. ohtusa by 

 Prosser (1894), PI. II, and those of Nathorst from Western Norway, Nathorst 

 (1915), should be added. It is now admitted that the Permian types from 

 Russia at one time included in this genus are in reality quite distinct. 



