324 
Notes . 
Leptosporangiatae, though these terms would still be retained in a 
descriptive sense. If the sub-orders Osmundaceae, Schizaeaceae, and 
Marattiaceae be transferred from the end of the ‘ Synopsis Filicum ’ to 
the beginning, and grouped with Gleichenia and Matonia, we have the 
Simplices before us. The Gradatae include the Cyatheaceae, Dick- 
sonieae (excl. Dennstaedtia ), Hymenophyllaceae, and Loxsomaceae, 
sequences probably of distinct descent, and, in my view, derivative 
from some prior forms such as the Simplices ; and in the arrangement 
of Sir William Hooker they hold a position following on the Gleicheni- 
aceae. The family of Dennstaedtiinae, founded by Prantl to include 
Dennstaedtia and Microlepia , also has its place here, but it leads on by 
intermediate steps to undoubtedly mixed forms such as Davallia , Cysto - 
pteris , Lindsay a, and the Pterideae. But this sequence is already laid out 
in this order in the Synopsis, and it illustrates one at least of the lines 
along which mixed forms are believed to have been derived from the 
Gradatae. No attempt has been made to follow the natural grouping 
of the Mixtae into detail, or to test the arrangement of them in the 
Synopsis. Sufficient has, however, been said to show that the systematic 
divisions of the Ferns now proposed fall in readily with the system of 
Sir William Hooker, notwithstanding that they are based upon details 
of which he cannot have been aware. 
