498 FILICALES 
are the dominant Ferns of the present day, while the Gradafae 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. 
Matonincas 
Simplices 
Loxsomaceae. 
Hymenophyllaceae. 
Gradatae + Dicksonieae (excluding certain genera). 
Dennstaedtiinae. 
\Cyatheaceae [Salviniaceae]? 
Dennstaedtia-Davallia series. 
-} Onoclea-W oodsia series. 
Matonia-Dipteris series. 
Pterideae and other Polypodiaceae 
Mixtae 
i 
BOTRYOPTERIDEAE.! 
The organisms grouped under this name occur as Palaeozoic fossils, 
extending upwards to the Permian.2 Though they are distinct from 
any other known family of Ferns, still there is no reason to doubt their 
Fern-nature: its recdgnition 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, 
1The materials for this description have been derived in the main from Renault, 
Bassin Houiller et Permien d’Autun et a’ Epinac, ii., p. 33, etc. ; Scott, Studies, p. 277, 
etc. ; Stenzel, Bd/otheca Botanica, 1889, No. 12; Scott, Progressus Ret. Bot., i, p. 178. 
I have also had the advantage of comparing specimens, chiefly those belonging to Mr. 
Kidston. 
2Mr. Kidston has shown me a Botryopterid (2. antigua) from the Petticur Beds, 
with axis and leaf bases showing structure. This he regards as probably the earliest 
record of a Botryopterts. 
