504 FILICALES 
that of the group of sporangia of Zygopteris shown in transverse section, 
which thus appear to constitute a radiate sorus (Figs. 272-3). Whether or 
not this is a constant feature in the latter Fern, it is clear that Corywepteris 
shows a sorus strongly suggestive of the arrangement in the Marattiaceae, 
a comparison already suggested by Scott.1 
The Botryopterideae have been recognised as a_ synthetic group, 
combining the characters of several known series of Ferns. The reasons 
for this opinion are to be found, first in their anatomical structure, and 
secondly in their sporangia. Though the leaves were relatively large, 
and much branched, and the petiolar structure often complex, the 
regularly radial axis remains relatively small, and its vascular structure 
exceedingly simple. The common occurrence of the undifferentiated 
protostele is regarded as a primitive character: added to this is the 
Fic. 273. 
A=Coryuepteris Essenghi, Andra (sf), from the Westphalian. Fragment of a fertile 
pinna. x6. B=Coryn. coralloides, Gutbier (sf), from the Westphalian. Fragment of 
a fertile pinna. 4. Sl=sorus of the same species seen laterally. x28. (After Zeiller.) 
simple origin of the leaf-trace from it. In both these characters the 
Botryopterideae compare with the simpler, strobiloid Pteridophyta, rather 
than with the more advanced Ferns. The sporangia are clearly of the 
Eusporangiate type, as evidenced by their massive stalk, relatively thick 
wall, broad non-specialised annulus, and the large spore-output. But 
their arrangement has not usually been recognised as being in definite 
sori; it is possible, however, that the terminal tassels of sporangia may 
have had some degree of regularity of orientation, such as is certainly 
suggested by Fig. 272-3. A slightly closer grouping of them together, 
coupled with a definite orientation such as that seen in Corynefterts, 
leads naturally to the type of sorus prevalent among the Marattiaceae. 
These Ferns diverge, however, very widely from the Botryopterideae in 
their mature anatomy. It will be seen later that on this point interesting 
comparisons may be drawn between the Botryopterideae and the 
Osmundaceae and Hymenophyllaceae, which are held to be relatively 
primitive groups, while they occur very early in the geological record. 
LLic.y Po 291. 
