380 Bower . — Studies in the Phytogeny of the Filicales. 
figures in Rabenhorst, but the venation of the tip in relation to the sorus, in 
cases where the latter stops short of it, is better seen in PI. XXV, Fig. 9. 
It shows the sorus distinctly intramarginal, with a flange on either side, into 
which short vascular strands pass. This is an advance on any of the species 
hitherto described ; in them the flange was a relatively insignificant structure 
without any vascular supply of its own. The sori are shown in Fig. 9 as 
shaded tracts stopping short of the apex ; a vascular commissure runs 
beneath each, connecting the veins, but this also stops short where the sorus 
ends. The arrangement of the veins and the relation of the commissure to 
them suggests very strongly that it is actually an extension of the anadromic 
branch of the furcate veins. This was the view held by Mettenius (Fil. Hort. 
Lips., p. 60, Taf. V, Fig. 5). 
The development of the fertile pinna begins in the usual way, by alter- 
nate cleavages of a marginal cell (PI. XXV, Fig. 10, a). But here the 
marginal cell takes its place quite definitely at the apex of the flange, which, 
as we have seen, is here of larger size proportionately than in previous 
examples. It may be seen to hold that position in Fig. 10, £, c, and the 
whole flange is referable in origin to it. But very soon a stronger growth 
appears on the abaxial face, at a point distinctly back from the margin 
(Fig. 10, b). It consists of a broad weal, several cells in section. The slope 
of this, which faces obliquely to the midrib, soon shows deeper cells 
(Fig. 10, c), which, undergoing segmentation, produce sporangia (Fig. 10,^). 
Though almost simultaneous in their time of origin, there are slight signs of 
a gradate sequence of the sporangia. It is closely adjoining the young 
sporangia on the side away from the midrib that the ‘ indusium ’ arises. We 
note that it is here relatively late in its origin, and is remote from the margin. 
Its structure when mature is shown in Rabenhorst’s Fig. 85. Its late appear- 
ance as compared with the species hitherto described, and its intramarginal 
position, maybe connected with its smaller size when mature, as an example 
of a principle of wide application. In respect of the time and place of appear- 
ance of the ‘ indusium ’, B. spicant may be held to be a more advanced type 
than those previously described, and to show a more clear case than any of 
them of the £ phyletic slide ’ of the indusium to the lower surface of the pinna. 
(G) Blechnum ccipense (L.), Schlecht. 
This very widely spread species, better known under its synonym of 
Lomaria procera , is of coarse habit, with stout ascending or erect stem, 
covered thickly with scales which extend also up the leaves, and form a very 
perfect protection to them while young. But in addition there are the 
glandular hairs of the B. brasiliense-ty^Q, which are so prevalent through 
the genus. Normally the leaves are strongly dimorphic and the fertile 
pinnae narrow, without any very prominent flange. But intermediate states 
are common, Sometimes the upper part of a leaf is fertile, and the lower 
