the more primitive type in the Ferns? 125 
are commonly found quite isolated. I think it probable that 
these sporangia are similar to those represented by Mr. 
Kidston, and described by him as ‘ annulate sporangia 1 ; ’ 
though possibly not specifically identical with sporangia 
represented in my figures, and though the internal cells are 
not represented in Mr. Kidston’s figures, still the corre- 
spondence of his sporangia to those examined by myself is 
certainly closer than to sporangia of Leptosporangiate Ferns. 
In searching among modern Ferns for sporangia structurally 
similar to these from the coal, I have found in Todea barbara 
a very remarkable resemblance : the main structural points 
of the Osmundaceous sporangium are already well known : 
their large size, and short stalk, the absence of a definite ring- 
like annulus, and dehiscence by a longitudinal slit. In 
longitudinal section the structure in Todea barbara is as in 
Fig. 6 : the most noteworthy characters for our present 
purpose are the irregularity of the external layer of cells, 
which is composed of relatively large, thick- walled cells at 
(a), while elsewhere the cells may be relatively small and thin- 
walled. Within this, and especially towards the base of the 
sporangium, will be seen small and compressed cells, limited 
by oblique walls, which remain till the sporangium is mature, 
constituting a partial and irregular inner layer (i, Figs. 6-8), 
while, in sporangia not quite mature, a granular film may be 
traced lining the cavity in which the spores are produced. 
The stalk of this large sporangium is relatively thin, and 
appears in the longitudinal section as composed of about 
four rows of cells. The whole construction of the sporangium 
is of a more bulky type than that of the typical Leptosporan- 
giatae, and I have elsewhere shown that this is its character 
from the very first stages of its development. In comparing 
this with the fossil sporangia, it is to be remembered that the 
1 Trans. Geol. Soc. of Glasgow, vol. IX, Part I, Figs. 11-13. In connection 
with Mr. Kidston’s use of the words ‘ annulate ’ and ‘ ex-annulate,’ it should be 
remarked that these terms are not to be taken as substitutes for ‘ Leptosporangiate ’ 
and ‘ Eusporangiate.’ The fact that an annulus is absent from the Hydropterideae, 
though these are typically Leptosporangiate forms, shows that precision is 
necessary on this point. 
K 
