Bower . — Studies in the Phytogeny of the Fi lie ales. 429 
logical probability has been pointed out, which gives a reasonableness to 
the comparative conclusions. 
Summary. 
1. For reasons which have been stated in the course of this memoir, 
the Ferns above treated as Blechnoid and Blechnoid derivatives are believed 
to represent a true phyletic sequence. 
2. Its origin has been traced in relation to the Cyatheoid Ferns. 
3. An actual point of probable contact has been found in Matteuccia 
intermedia , C. Chr. 
4. From such a source appear to have sprung several divergent lines. 
The main line leads through § Lomaria to Eu-Blechnum . 
5. This involves the origin of the ‘ flange and diversion of the 
‘ phyletic margin ’ to indusial functions, as the structure styled by the older 
writers the ‘ false indusium ’. 
6. Minor lines led to Acrostichoid derivatives, respectively in Steno- 
chlaena and Brainea. 
7. Interruption of the fusion-sorus, foreshadowed as an anomaly in 
Blechnum , led to the states shown in Woodzvardia and Doodia. 
8. An outward arching of the fusion-sorus of Blechnum , ultimately 
combined with interruption, foreshadowed in the varieties of B . punctulatum , 
gives the key to the origin of Scolopendvium. 
9. An outward swinging of the interrupted fusion-sori, variously 
combined with archings and new formations of partial sori, and various 
branchings of the leaf, give the several types of Asplenium. 
10. The relation of Plagiogyria to the whole series is problematical. 
It seems probable that it is an isolated, as it is certainly a relatively 
primitive, genus. 
11. All the Ferns here considered belong to the Superficiales. But in 
the methods of their advance they show interesting parallels with repre- 
sentatives of the Marginales. 
Glasgow, Dec. 1913. 
EXPLANATION OF FIGURES IN PLATES XXII-XXXII. 
Illustrating Professor Bower’s paper on Blechnum and Allied Genera. 
PLATE XXII. 
Fig. 1. Transverse sections of young pinnae of Plagiogyria semicordata , in successive stages of 
development, a shows that the whole wing of the pinna is referable in origin to marginal 
segmentation, b shows a more advanced state, in which the extreme margin is growing out to 
form the thin ‘ indusial ’ dap, which arches over the receptacle below it. Mucilage-hairs are also 
seen, c shows a section of a mature pinna, with fully formed dap covering the mature sporangia, 
x 125. 
