504 FILICALES 



that of the group of sporangia of Zygopferis 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 Corynepteris 

 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 



ir 



FIG. 273. 



A Corynepteris Essenghi, Andrae (sp\ from the Westphalian. Fragment of a fertile 

 pinna. X6. B = Coryn. coralloides, Gutbier (sp\ from the Westphalian. Fragment of 

 a fertile pinna. X 4. B l = sorus of the same species seen laterally. X 28. (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 Corynepteris, 

 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. 



1 L.c., p. 291. 



