GENERAL RESULTS— PTEROPSIDA 653 



by any direct relation to the Cycads, but by common 

 descent from an early Pteridospermous stock. 



The Pteridospermous affinities of the Cordaiteae 

 have an important bearing on ■ the question of the 

 systematic position of the Coniferae. It has generally 

 been recognised that the Cordaiteae are related to the 

 Coniferae, and if this be so, it follows that the latter 

 are also ultimately of Pteridospermous descent, and 

 thus belong to the great phylum of the Pteropsida. 



Some authors, however, have endeavoured to derive 

 the Conifers from the Lycopodiales, 1 while others have 

 limited this theory to a portion only of the Coniferae, 2 

 implying that the order is an artificial assemblage, 

 made up of at least two unrelated groups. 



Of late the question has turned especially on the 

 position of the Araucarieae, which Professor Seward has 

 regarded as probably of Lycopodineous origin, while he 

 leaves the question open for the rest of the Coniferae. 3 

 Some brief discussion of the question seems necessary 

 here, as the issue involved is that of the single or 

 multiple origin of the existing Spermophyta. The 

 position of the Araucarieae will be primarily con- 

 sidered, since it is this group especially which is now in 

 dispute. 



1 E.g. D. H. Campbell, Lectures on the Evolution of Plants, New 

 York, 1899, pp. 166-167. 



2 JZ,g, H. Potoni£, Lehrbuch der Pflanzenpaliiontologie, Berlin, 1899, 



p. 32°- 



3 A. C. Seward and S. O. Ford, "The Araucarieae, Recent and 



Extinct," /%z7. Trans. Royal Soc. B, vol. 198, 1906, pp. 3°5-4H- See 

 also the " Report of a Discussion on the Origin of Gymnosperms at the 

 Linnean Society," New Phytologist, vol. v. 1906, pp. 68 and 141, where 

 the views of various botanists are briefly given. 



