Bower. — Studies in the Phytogeny of the Fili cates. 301 
with proportionately large meshes, from the lower margins of which are 
given off two large strap-shaped strands to the subtending leaf. There is 
a central pith which is very voluminous in proportion to the other tissues, 
so that the ring of meristeles lies very near to the periphery. It is to be 
noted that sclerenchyma is absent from it, in marked contrast to what is 
seen in the Cyatheaceae. In fact, the structure of the stock is strikingly 
similar to that of those species of Nephr odium which have a binary leaf- 
trace, such as N. 0 reop ter is. 
The general character of the fertile leaf of X. orientalis resembles that 
of S. germanica and Onoclea sensibilis. The venation of the fertile pinna is 
on the same plan as that of the sterile pinna, but the branches of each vein 
from the midrib are only 5-6 as against 10-12 in the sterile. Anastomoses 
are again entirely absent in 5 . orientalis. The lowest branch of each vein 
is katadromic (PI. XXXVI, Fig. 36). Each branch may bear a single sorus, 
as in X. germanica , but whereas there the sori of the lower branches are 
slightly nearer to the midrib than those of the upper, in X. orientalis they 
are all at an equal distance, so as to constitute a regular intra-marginal row. 
This will be found to be matched by Blechnum capense (see Mettenius, 
‘ Filices Horti Lipsiensis,’ PI. IV, Fig. 21). Each vein is continued a short 
distance beyond the insertion of the sorus, but stops short where the 
margin of the pinna curves over as a continuous protective flap, which in 
this species is firm, and coloured brown. In addition to this protection 
each sorus is, as in S. germanica and Onoclea , covered by a shell-shaped 
indusium, attached at the side next the midrib. It is structurally of the 
nature of a ramentum or scale. A section through a sorus from one of 
Messrs. May's plants shows how the leaf-margin overlaps the scale 
indusium, the protection of the sorus being a very efficient one (Fig. 37). 
But in the specimens from India the indusium does not appear to be present. 
The receptacle in S. orientalis , as seen in specimens from the Glasgow 
Garden, is a rather flat one, being hardly raised beyond the general level 
of the leaf-surface (Fig. 37). A tract of tracheides rising from the vascular 
strand which underlies it brings supplies to the sporangia. These are 
relatively few in number, as seen in the Glasgow specimens ; but in the 
normally grown specimens from India the sori are larger, the receptacle 
more raised, and the sporangia more numerous. There is an evident 
basipetal succession of the sporangia, as has already been demonstrated 
for Onoclea sensibilis and X. germanica (Studies, IV, PI. V, Fig. 90). This 
is apparent even from the drawings from garden plants, for the central 
sporangium at the apex of the convex receptacle is the most advanced, and 
the lateral sporangia younger. 1 
1 The absence of an indusium in the specimens from India, together with the much larger receptacle 
and more numerous sporangia, suggests further inquiry as to specific identity of the specimens. The 
Glasgow plants correspond most nearly to the specific descriptions for Struthiopteris orientalis . 
