D. H. Scott. 
118 
section is of interest as showing the palisade-like hypodermal layers 
of the branchlet ; the tissue is, however, denser in this position 
than on the larger branches of the rachis. Here, again, the 
sporangium is full of well-preserved spores. 
In the specimen represented in Fig 2b, only a short piece of 
the rachis bearing the sporangium is preserved, but the continuity 
of the tissues is especially well shown. In this case the sporangium 
is cut tangentially, so that only a comparatively small part of the 
spore-containing cavity is exposed. 
A few details as to the sporangia themselves may now be 
added. 
In form the sporangium is nearly spherical; in six sporangia 
measured the average dimensions were 740/* x 640/*. The larger 
diameter is sometimes transverse, sometimes longitudinal, and we 
cannot suppose that the exact natural form is retained. The 
natural dimensions may have been slightly in excess of those given, 
as the sections would seldom be precisely median. 
The outer layer of the sporangial wall is formed of square or 
columnar cells about 50/* in height, the width varying from 24/* 
to nearly 50/*. Nothing of the nature of an annulus has been observed 
in any of the numerous sections examined, but on the side opposite 
the attachment of the sporangium there is a well-marked stomium 
of small cells only about 20/* in height (Fig. 2a). In some cases 
the dehiscence of the sporangium through the stomium is clearly 
shown. 1 In all well-preserved specimens there is a fairly thick 
lining tissue within the outer wall; it consists of several layers of 
small thin-walled cells, and seems to have been interrupted only at 
the stomium. The lining tissue is continuous below with the 
parenchyma of the supporting rachis. Remains of this tissue are 
found even in old and empty sporangia (Fig. 1). The spores are 
approximately spherical in form, with a diameter of 32—40/*. The 
wall is smooth ; in favourable cases the triradlate marking can be 
clearly recognized, indicating that the spores were of the tetra¬ 
hedral type. No indications of a multicellular structure have 
been detected. 
The results of the present preliminary investigation, which I 
hope before long to be able to pursue further, may be summed up 
as follows:— 
Stauropteris oldhamia , Binney, in the form in which it 
In Fig. 2c, however, it is doubtful whether the bursting of 
the sporangium was natural. 
1 
