122 Morphology BOOK i 



dendreae. The question was investigated almost at the 

 same time by Potonie. In consequence of these re- 

 searches a new group came to be recognized, the Cyca- 

 dofilices, a name suggested by Potonie in 1897. Scott 

 held that the two forms he particularly studied were 

 derivatives of an ancient non-specialized Fern-stock, and 

 in 1899 he expressed the opinion that this common stock 

 is to be sought among simple Ferns or fern-like plants. 



From this stock we are led, therefore, to derive the existing 

 Ferns, and, at any rate, one phylum of the Gymnosperms. 

 In the speculations which followed, supported it is true by 

 hardly any evidence, the Cycadofilices were suggested as 

 ancestors of the Ginkgoales and of the Coniferae through 

 the extinct Cordaiteae, as well as of the Cycads. The 

 Bennettiteae were also spoken of as probably intermediate 

 between Cycadofilices and C3^cads. Other workers declined to 

 abandon the theory of the descent of the Conifers, or some 

 of them, from the hypothetical Lycopodiaceous ancestor, 

 a theory supported by Seward as a result of his examination 

 of the Araucarieae. It was a time of speculative ideas, 

 when the task of drawing up hypothetical genealogical 

 tables exerted a strange fascination on the minds of many, 

 carried away by the startling discoveries obtained from the 

 records of the rocks. 



The last theory of the classification of the vascular plants 

 put forward prior to the close of the century was Jeffrey's 

 scheme of 1900. He based it on anatomical considerations, 

 making two large groups the Lycopsida, possessing a 

 cladosiphonic stele and bearing small leaves, and the 

 Pteropsida, with a phyllosiphonic stele and usually develop- 

 ing large leaves. Lycopsida included the Lycopodiales 

 and the Equisetales, among the latter of which he put 

 the Sphenophyllales, while Pteropsida comprised the 

 Filicales, Gymnospermae, and Angiospermae. 



Jeffrey claimed that the anatomical structure of the 



