282 FILICALES [CH. 



ferns, some authors went far towards concluding that however 

 close might be the agreement between fossil and recent leaves 

 suspicion of close relationship must be set aside. Like the 

 earlier writers who described fossils as lusiis naturae fashioned 

 by devilish agency to deceive too credulous man, the discovery 

 of seed-bearing plants with the foliage of ferns threatened to 

 disturb the mental balance of palaeobotanists. The fact is, 

 we cannot in some cases determine from leaf-form alone whether 

 or not a fossil is a true fern; we may, as Professor Bower^ 

 suggests, regard all fern-like fossils as ferns until they are 

 proved to be Pteridosperms, or in a spirit of scientific scepti- 

 cism, we may at once admit that many Palaeozoic fern-like 

 leaves must await further evidence before their true position 

 can be determined. It is impossible, as Zeiller^ says, in the 

 present state of our knowledge to range fern-like Palaeozoic 

 plants in two groups, one referred to Filicineae and the other 

 to the Pteridosperms. 



The following classification of the Filicales is based on 

 that adopted by Prof. Engler in the latest edition of his 

 Syllabus^ and on the results of Bower's* excellent work on the 

 spore-bearing members of recent ferns. 



The members of the Filicales are characterised by the same 

 well-marked physiological division of labour in their vegetative 

 parts as are the Lycopods ; the plant is the asexual generation 

 (sporophyte), while the sexual generation (gametophyte) is 

 small and inconspicuous, either an independent green prothallus 

 or a tissue more or less completely enclosed in the spore. The 

 large size of the leaves, which in the young state are usually 

 coiled like a crozier (fig. 220, A), is a striking characteristic of 

 the ferns ; they are megaphyllous in contrast to the microphylly 

 of the Lycopods. 



1 Bower (08). 2 Zeiller (06) p. 8. 



» Engler (09). •» Bower (00). 



