Bower —Studies in the Phytogeny of the Filicales. 289 
midal cell at the apex of the upgrowing sporangium. From this by 
a periclinal wall the cap-cell is cut off. The number and relations of the 
cells which thus go to form the stalk of the sporangium do not appear to 
be precisely the same in all cases. The stalk which results is of a massive 
type (Figs. 25, 26). The whole segmentation of the sporangia, as well as 
their position on the receptacle, and the structure of the latter are strongly 
reminiscent of what has been demonstrated for Gleichenia linearis ( =G . 
dichotoma ) some years ago (Studies, IV, PI. II, Figs. 15-17). In both 
cases the relatively thick stalk is indicative of a primitive sporangial type. 
On the other hand, a comparison may be instituted with the young 
sporangia of the Cyatheaceae, as shown for Cyathea ( 1 . c., Figs. 78-80)) 
for Alsophila (l.c., Fig. 87), and for Onoclea (l.c.» Fig. 90). It is, how- 
ever, to be remarked that in these the sporangium is of a rather more 
attenuated form, and projects more in its early stages of segmentation, 
which is an indication of its more advanced state. 
A later state of the sorus and sporangia is shown in Figs. 28, 29, 
the former being cut so as to follow the course of the vein over which it is 
seated, while in the latter the vein is cut transversely. From the convex 
surface of the receptacle arise numerous hairs, which show a basal inter- 
calary growth. The sporangia are few, and are always of uniform age 
in the sorus. There is no evidence of any succession in their appearance. 
Thus Lophosoria would be properly ranked, as Gleichenia is, among the 
Simplices. It may be noted that the sporangia in Lophosoria are raised 
further from the surface of the leaf than in Gleichenia (compare Figs. 28, 29 
with Figs. 22, 24 of Studies, IV). This is owing to the greater height 
of the receptacle, a fact which accords with its relation to the Cyatheaceae, 
where the receptacle is higher still. 
As regards the sporangia, their position when young naturally corre- 
sponds with that which they hold when mature. In Fig. 28 two are 
traversed in positions corresponding to those of Gleichenia linearis , as seen 
in Fig. 15 of Studies, IV. In Fig. 29 three are seen corresponding in their 
disposal to those of G. linearis shown in Studies, IV, Fig. 16. The 
sporangia themselves have their short massive stalk segmented in a way 
that would lead to a structure as seen in Fig. 17. It corresponds to that of 
G. linearis , rather than to the more massive structure seen in G. circinnata. 
The sporangial head has as usual the single peripheral layer of cells that 
will form the sporangial wall, lined with the tapetal layer, which surrounds 
the single sporogenous cell. The structure and proportions thus seen for 
Lophosoria are of a type common for the more primitive Ferns where the 
sporangium is large, such as Gleichenia linearis , Matonia , or L ox soma, 
but not of the very largest size. As it grows older the annulus begins to be 
differentiated by enlargement of certain cells of the wall (Figs. 30-2), the 
tapetal layer divides in the usual way into two, and the sporogenous cell 
