The Present Position of Palaeozoic Botauy. 189 



certain number of Marattiaceous Ferns, especially in the later Carboni- 

 ferous and Permian periods, though we may not always be able to 

 distinguish their fructifications from the pollen-bearing organs of 

 Fern-like seed-plants. Whether this surprising similarity is merely a 

 case of "parallelism of development" as Mr. Arber suggests, or is 

 indicative of affinity, must be left an open question. A direct affinity 

 seems improbable, but it must be remembered that in Corynepteris we 

 appear to have the sporangia of Botryopterideae grouped in synangia 

 like those of Marattiaceae, and it is possible that in Sturiella (Fig. 17, D) 

 we may have another case of the same kind. It is therefore a 

 not improbable conjecture that Marattiaceae and Pteridospermeae 

 may owe their synangic fructifications to common descent from a 

 primitive group of Filicales in which the character had already 

 appeared. 



From what has been said above, it will be evident that our 

 knowledge of Palaeozoic Ferns is now in a transitional and somewhat 

 unsatisfactory condition. The old ideas of their predominance have 

 gone, never, probably, to return. There is no longer any presumption 

 that a Fern-like frond really belonged to a Fern; even where some 

 of the reproductive characters seem to point the same way, the in- 

 ference, as we see in the case of Crossotheca. may be quite fallacious. 

 We now have to seek laboriously for evidence, which formerly seemed 

 to lie open to us on all hands. I believe, however, that such careful 

 investigation will result in the resuscitation of the Palaeozoic Ferns 

 as a considerable, though not as a dominant group. The petrified 

 material, on wiiich we now have chiefly to rely, indicates the presence 

 of true Ferns ^), not only in the Upper but in the Lower Carboni- 

 ferous, and if this is so there is no reason to doubt that they extended 

 back as far as any Vascular Plants. Eventually we may hope to be 

 able to recognize them in the form of impressions, though now it is 

 only in rare cases that we can distinguish such specimens with 

 certainty from the foliage of Fern-like Spermophyta. 



At present our knowledge of the Palaeozoic Ferns centres in the 

 group Botryopterideae. the type-family of that ancient Filicinean 

 stock, which has now come to be of supreme interest in the geological 

 history of Vascular Plants. 



^j I use this phrase, uot in the limited sense in which Mr. Kids ton employs 

 it, hut to include all Cryptogamic Filicales as distinguished from Fern-like Seed- 

 plants. 



