Bower.—Studies in the Phytogeny of the Filicales . VII. 11 
It is thus apparent that, while in all the Schizaeaceae the origin of the 
sporangia is actually marginal, some of them suggest a transition from the 
marginal to the superficial position, and Mohria provides a pregnant 
example. Further, it is seen that indusial flaps of various form arise in 
point of fact superficially, after the marginal initiation of the sporangia 
which they then protect. Such facts are important for comparison with 
other types of the Marginales. One related phylum is suggested by 
Loxsoma and the Hymenophyllaceae; another by the Dicksonieae. In 
both the receptacle and the indusial flaps, which are double, precede the 
first sporangia in point of time. Their relation to the Schizaeaceae has 
already been discussed elsewhere. 1 Here it is the Pterideae which will 
engage special attention, with a view to assigning their approximate phyletic 
position. It will then be possible to take up more effectively the discussion 
of the phyletic relations of these and other large series of Ferns, which 
may be held to have sprung from types in which the sorus was marginal. 
Pterideae. 
The limits and the internal grouping of the Ferns included under this 
heading have varied in the hands of successive systematists. 2 Though in the 
main there is naturally some similarity between the several arrangements, it 
cannot be said that in any one of them the prime object has been a grouping 
by descent. Systematic convenience and the inclusion under concise and 
readily handled diagnoses have been more evident in them than the 
searching out of real affinities. Naturally the systematic grouping must as 
a rule have the effect of placing related forms in near proximity ; but there 
has been little attempt at the laying out of evolutionary sequences. 
Of all the recent Fern-systematists Prantl was the writer who most 
readily took phyletic views, while his basis for comparison was extended as 
a consequence of his excellent technique. The result appears in his 
grouping of the Pterideae, which, though open to amendment, is more 
acceptable than the rest of his system. 3 He divides his Pterideae thus : 
1. Lonchitidinae , sorus marginal: spores tetrahedral, or bilateral: hairs 
simple cell-rows. Lonchitis , Pteridium , Paesia. 
2. Pteridinae. Sorus superficial, upon the back of the unthickened 
nerve-endings, and extending thence for various distances downwards. 
Hairs are flattened scales ; spores tetrahedral. Cheilanthes , Pellaea i 
Adiantum , Cryptogramme , Pteris. 
3. Gymnogramminae. Sorus superficial upon the back of the un- 
1 Land Flora, p. 587. 
2 Compare Presl’s Tentamen (1836) ; Hooker, Synopsis Filicum (1868) ; Prantl, Das System 
der Fame (1892); Diels, in Natiirl. Pflanzenfam., i. 4 (1902); Christ, Farnkrauter (1897) ; and 
Christensen’s Index (1906), which follows the grouping of Natiirl. Pflanzenfamilien. 
8 Arb. Konigl. Bot. Gart. zu Breslau, 1892, pp. 16-17. 
