Bower —Studies in the Phylogeny of the Filicales. 297 
which is common in the Cyatlieaceae. The internodes are longest in the 
creeping lateral buds of Lophosoria , while in the upright shoots the leaf-gaps 
sometimes overlap, giving an elementary state of dictyostely. This is 
exactly what would result if a shoot of the type of G. pectinata were to 
adopt an erect habit. The leaves themselves, being of necessity mechanically 
self-supporting, must have relatively broad bases of insertion. The axis 
would necessarily be shortened, and become more bulky to accommodate 
the more crowded and relatively broad bases of the leaves. That condition 
is already seen in Lophosoria , but the leaf-gaps do not usually overlap. 
But they do overlap in the typical species of Alsophila , which are thus 
dictyostelic. Lophosoria forms accordingly, in the vascular characters of 
its axis, an intermediate step between the two types, as it does also in habit, 
and in other features. 
The leaf-trace of Lophosoria comes off as a single broad strap, and 
often passes undivided up the leaf. But where the leaf is large it commonly 
divides up into three parts, though this separate course does not continue 
far, the three joining again into a single strand below the lowest pinnae. 
A very similar condition is seen in Plagiogyria semicordata (‘ Ann. of Bot.’, 
xxiv, p. 431), and in some other Ferns. Such cases have their interesting 
bearing upon general views of the leaf and the relative primitiveness of its 
parts, a subject which will be held over for the present. From the com- 
parative point of view Lophosoria in this detail again takes a middle place 
between Gleichenia , in which no such partition of the trace has been recorded, 
and the Cyatheaceae, where the dissolution of the trace into separate strands 
is present in much higher degree, and extends much further along the leaf 
than in Lophosoria. Further, in the horseshoe form of the trace, with its 
deep lateral depressions, as well as in the origin of the pinna-trace, Lopho- 
soria also takes an intermediate place, but with a decided leaning to the 
Cyatheaceae. This comes out particularly in the large number of the 
£ divergents ’, and in the corrugation of the trace in accordance with their 
position. Thus the general conclusion from an anatomical comparison is that 
while the affinities of Lophosoria are distinctly with the Cyatheaceae, it shows 
in a number of anatomical features, which may themselves be held as primi- 
tive, a condition intermediate between that family and the Gleicheniaceous 
type. And among the latter it approaches most nearly to G. pectinata. 
5. But it is upon the characters of the sorus, its position and its 
constitution, that the most frequent comparisons have been made. In the 
Gleicheniaceae, as in the Cyatheaceae, the venation of the fertile pinnule is 
without any fusions, except occasionally in Hemitelia. The veins fork, but 
not very profusely, and the branches run out free to the leaf-margin. In 
fact, in both the venation is of the primitive, Pecopterid type. In Lophosoria , 
as also in G. linearis and pectinata , the sorus is constantly seated upon the 
anadromic veinlet of the ultimate pinnule. This uniformity in position, com- 
