meristems of Ferns as a Phylogenetic Study . 369 
I. Hymenophyllaceae. 
II. Cyatheaceae. 
III. Polypodiaceae. 
IV. Gleicheniaceae. 
V. Schizaeaceae. 
VI. Osmundaceae. 
VII. Marattiaceae. 
VIII. Ophioglossaceae. 
This arrangement is also observed by Goebel 1 ; though, oddly 
enough, the position of the Schizaeaceae and Osmundaceae is 
reversed where the special description of the groups is given 
( 1 . c. p. 238). This same reversed position is adopted also by Van 
Tieghem 2 ; and from these facts I conclude that these authors 
had not recognised the near affinity of the Osmundaceae to 
the Marattiaceae. Prantl 3 suggests that the isosporous Ferns 
may be arranged, in respect of their general characters, in 
three groups, as follows : — 
I. II. III. 
Hymenophyllaceae. 
Polypodiaceae. 
Cyatheaceae. 
Schizaeaceae. 
Gleicheniaceae. 
Parkeriaceae. 
Osmundaceae. 
Ophioglossaceae, 
Marattiaceae. 
He recognises the affinity more especially of the Schizaeaceae 
to the third group, and, on grounds which appear to me to be 
insufficient, especially to the Ophioglossaceae, rather than to 
the Osmundaceae or Marattiaceae. 
It is thus seen that of the intermediate divisions of iso- 
sporous Ferns, the close relation of the Polypodiaceae and 
Cyatheaceae has been recognised by all the authors above 
quoted, and these two groups are placed by them next to the 
Hymenophyllaceae ; this I believe to be their true position, 
and this conclusion is also borne out by the study of their 
meristems. The details of structure and development of the 
Gleicheniaceae are too imperfectly known to allow of their 
1 Outlines, p. 194, Engl. ed. 2 Traite de botanique, p. 1256. 
3 Schizaeaceae, 1881, p. 15 1. 
