Bower . — Studies in the Phytogeny of the Fiticales. 42 1 
Sadleria, and in Doodia blechnoides. It may be held as an advance upon the 
simpler type, and the result is seen in varying degrees of complexity of the 
petiolar system (Text-fig. 20). 
But in Stenochlaena sorbifolia and in Woodwardia radicans the trace is 
more complex at its origin. The lateral strands are present as before, but 
lower down than their insertion smaller leaf-trace strands arise separately 
from the foliar gap, and pass into the median region of the horseshoe series. 
Technically, the leaf-trace consists here not of two strands, but of five 
or six, a condition of advance as compared with the usual Blechnum type 
(Text-figs. 11, 16). 
Lastly, median vascular fusion makes its appearance in the petiole, 
in certain forms. This may be seen in a rather unusual position occasionally 
in B. attenualum (Text-fig. 20, 4), but it is a marked feature in those 
genera which we regard as derivative, viz. Scolopendrium and Asplenium . 
It may be regarded as a secondary feature (see Rab. Krypt.-Flora, iii, 
pp. 120, 151). 
The result of these anatomical comparisons is a general support of the 
natural affinity of the Ferns in question. But they do not give much 
detailed guidance in their phyletic sedation. The fact is clear, however, 
that the more complex leaf-traces are found in those types which on their 
soral characters are held to be the more advanced, such as Stenochlaena and 
Woodwardia. Also the vascular fusions in the leaf-base, which are so fre- 
quent in Scolopendrium and Asplenium , mark these genera out by a feature 
which is certainly derivative from the common type. Thus, so far as it 
goes, the anatomical evidence is in accord with the soral conclusions, and 
supports them. 
Soral Characters. 
In proportion as other criteria fail us in greater or less degree, stress 
must be laid upon the soral characters for the phyletic treatment of the 
Blechnoid Ferns ; and fortunately their sori provide a considerable range 
of divergent detail. On a basis of modern comparison, as well as on that 
of traditional opinion of the older systematists, the soral relation has been 
recognized between Matteuccia and Blechnum (compare Ann. of Bot, xxvi, 
PL XXXVI, Figs. 26-37). While both are dimorphic, with marginal pro- 
tection of the sori, one important point of difference between them consists 
in the presence of a ‘ true ’ indusium in Matteuccia as hitherto described, 
and its absence in Blechnum. But it is now seen that this is not a constant 
distinction. The ‘ true * indusium is absent from the new species M. inter - 
media, C. Chr. ; it is not even present in that species in the youngest state 
of the sorus. Accordingly, the starting-point for the nearer comparison 
of the Blechnoid Ferns will be a type corresponding to Alsophila , in having 
a basipetal sorus seated upon a vein, without any indusium. The chief 
soral difference between Alsophila and M. intermedia lies in the minor 
