Bower . — Studies in the Phytogeny of the Fi lie ales. 4 1 3 
If, now, these extra sori were extended downwards beyond the point of 
branching of the vein that supports them — a condition which may be actually 
seen in var. Krebsii and in Camptosoms (compare Mettenius, 1 . c., Taf. V, 
Fig. 6, bb) — the result would be that of Diplazium with the sori back to 
back on an unbranched vein. 
The most complex Asplenioid forms are found in those gigantic Ferns 
associated under the name of Callipteris , Bory (= Anisogonium, Presl). 
They are characterized by having the veins variously anastomosing. A par- 
ticularly interesting example is seen in Diplazium ( Callipteris ) ceratolepis , 
Christ, from Costa Rica, described by Dr. Christ in Bull. Soc. Bot. Belg. 35, 
p. 203. It appears to connect the Callipteris type with the Blechnoid model, 
and to show in a less condensed form the same method of soral arrangement 
as is seen in Scolopendrium , while the relation of the pinnules to the soral 
arches corresponds to that of the suppressed pinnae of the latter. Its leaf 
is very large and pinnate ; the pinnae are pinnatifid. The nervation of 
a part of one of them is shown in Fig. 703 of Christ’s Farnkrauter, p. 222. 
It differs from most types of Asplenium in having arched veins running 
nearly parallel to the midrib between the main veins, corresponding in 
position to the commissural arches of B. punctulatum , var. Krebsii ) or of 
Brainea. Like the latter Fern, the indusium appears to be absent, while 
the sori spread far outwards along the veins. This Fern would repay 
a complete study. But this, as also the more exhaustive analysis of the 
whole genus Asplenium , must be left over for the present. 
The development of the sorus of Asplenium is quite in accord with the 
conclusions which follow from the comparisons thus made. Its origin is 
after the model of the most advanced Blechnoid types. The marginal 
segmentation of the pinna appears as usual, and produces a lateral wing. 
After this has attained considerable size the indusium and receptacle make 
their appearance at a point distinctly intramarginal. This is shown in 
PI. XXXII; Fig. 36, a , b , c , for the bulky species A. obtnsatum , Forst. The 
indusium develops quickly, and in this species it consists at first of a single 
layer of cells ; later it may become more massive at the base. The concave 
surface covered by it is the receptacle, from the deep cells of which the 
sporangia arise. These show a distinctly ‘ mixed ’ character in the order of 
their appearance. The relations of the sorus respectively to the margin and 
to the midrib are thus seen to be substantially the same as those of advanced 
types of Blechnum , or of the less-divergent varieties of B. punctulatum , such 
as var. Atherstoni. 
Sections were also cut from the leaves of A. nidus , L., in various stages, 
and they showed substantially the same arrangements as A. obtusatum , 
except that the sori were more crowded upon a still more fleshy leaf. As 
an example of a Diplazioid type, A. {Dipl.) celtidifolium , Kze., was cut. The 
leaf is here more delicate in texture, but, putting this aside, the structure of 
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