498 



FILICALES 



are the dominant Ferns of the present day, while the Gradatae take a 

 middle place. This succession will be maintained in the detailed account 

 of the several families, and consequently the description will follow in 

 the main, though not in exact detail, the order of appearance of the 

 several families of Homosporous Ferns upon the earth's surface. The 

 order in which they will be taken up will be as follows : 



Botryopterideae. 



Marattiaceae (together with many Pecopterids). 

 Osmundaceae. 



Schizaeaceae [Marsiliaceae] ? 

 Gleicheniaceae. 

 iMatonineae. 



Simplices 



Gradatae 



Mixtae 



fLoxsomaceae. 

 Hymenophyllaceae. 



Dicksonieae (excluding certain genera). 

 Dennstaedtiinae. 

 .Cyatheaceae [Salviniaceae] ? 



f Dennstaedtia-Davallia series. 



Onoclea-Woodsia series. 



Matonia-Dipteris series. 

 .Pterideae and other Polypodiaceae. 



BOTRYOPTEKIDEAH. 1 



The organisms grouped under this name occur as Palaeozoic fossils, 

 extending upwards to the Permian.'-' Though they are distinct from 

 any other known family of Ferns, still there is no reason to doubt their 

 Fern-nature : its recognition is based not only upon the external characters 

 of the shoot, with the usual circinate vernation of the leaves, but also 

 upon the anatomical details of axis and leaf, and upon the fact that the 

 numerous sporangia are borne upon the distal region of the repeatedly 

 pinnate sporophylls. Finally, in Stauropteris Oldhamia Scott has shown 

 that the spores possessed the capacity for germination within the 

 sporangium, as in some modern Ferns. 



The plants had an erect shoot of radial construction : it was sometimes 

 short, with closely aggregated leaves, as in Grammatopteris Rigolloti, 



1 The materials for this description have been derived in the main from Renault, 

 Bassin Hoitiller et Permien cfAnlitn ,'t d ' Epi/iai . ii., p. 33, etc. ; Scott, Studies, p. 277, 

 etc. ; Stenzel, Bibliotheca Hotnuica, 1889, No. 12; Scott, Progress us Rei. Bof., i., p. 178. 

 I have also had the advantage of comparing specimens, chiefly those belonging to Mr. 

 Kidston. 



-Mr. Kidston has shown me a Botryopterid (/>. antiqita) from the Petticur Beds, 

 with axis and leaf bases showing stiucture. This he regards as probably the earliest 

 record of a Botryoptens. 



