638 STUDIES IN FOSSIL BOTANY 



The question of a possible relationship between the 

 Palaeozoic Lycopods and certain Seed -plants will be 

 discussed when we come to the Gymnosperms. 



PTEROPSIDA 



The result of the palaeobotanical research of the 

 last twenty years has been to exalt the importance of 

 the Fern phylum, which now appears to have been the 

 source from which the great majority, if not the whole, 

 of the Seed-plants were derived. At the same time the 

 recent discoveries have greatly reduced our estimate of 

 the actual number of the true Ferns in Palaeozoic times 

 (most of them having already become Seed-plants at 

 that period), and difficulties have arisen in discriminat- 

 ing between the Ferns proper and their more advanced 

 allies the Pteridosperms. Any certain knowledge of 

 Palaeozoic Filices is, for the moment, practically limited 

 to the family Botryopterideae and- a few other forms 

 probably allied to them. We may follow Mr. Arber 1 

 in using the name Primofilices for the whole group. 

 As regards the Marattiaceae, long considered as the 

 dominant Ferns of the Carboniferous period, the ques- 

 tion is much more difficult, as has been shown in 

 Chapter VIII. 



There is no reasonable doubt that the Botryo- 

 pterideae were true Ferns ; all their characters, both 



were borne on the under side of the sporophyll, there is great difficulty in 

 accepting this view. On Pleuromeia see Solms-Laubach, " Ueber das 

 Genus Pleuromeia" Bot. Zeitung, Bd. lvii. 1899, p. 227 ; H. Fitting, 

 ' ' Sporen im Buntsandstein — die Makrosporen von Pleuromeia ? " Per. d. 

 Deutschen Bot. Gesellschaft, Bd. xxv. 1907, p. 434. 



1 E. A. N. Arber, " On the Past History of the Ferns," Ann. of Bot. 

 vol. xx. 1906, p. 221. 



