CH. XX] PTERIDOSPERMS 281 



test of unbiassed examination, they must at least lead us 

 to substitute a critical consideration of the facts for a mere 

 repetition of conclusions which appeal to our imagination. 

 Despite Prof. Chodat's warning, we may still quote with con- 

 fidence a phrase used in another connexion — ferns "are links 

 in a chain and branches on the tree of life, with their roots in 

 a past inconceivably remote^" 



Transitional forms which are regarded as pointing to a 

 common origin for ferns and cycads are known in abundance ; 

 other types have also been discovered which lead some authors 

 to go so far as to derive the whole of the seed-bearing plants 

 from an ancestry the descendants of which are represented by 

 existing ferns. While hesitating to allow the ferns or fern-like 

 plants the peculiar position of universal ancestors, we must 

 admit that there is no group of plants with a history of greater 

 importance from an evolutionary standpoint than that with 

 which we are now concerned. 



There are, however, some difficulties to face in attempting 

 to decipher the history of the Filicineae as recorded in the 

 earth's crust. Few fossil plants are so familiar as the well- 

 preserved carbonaceous impressions of compound leaves on the 

 shales of our Coal-Measures, which were referred by older authors 

 to recent genera and species of ferns and accepted by later 

 writers as undoubted examples of Palaeozoic ferns. The common 

 belief in the dominance of ferns in Palaeozoic floras is reflected 

 in the novelist's description of the Carboniferous period, "when 

 the forms of plants were few and often of the fern kind I" We 

 now know that very many of these Carboniferous leaves be- 

 longed to plants differing widely in morphological characters 

 from the modem genera to which they exhibit so deceptive 

 a resemblance. These pseudo-ferns, recently christened Pteri- 

 dosperms or seed-bearing fern-like plants, are dealt with in a 

 later chapter. The discovery of this extinct group has added 

 enormously to our knowledge of plant-evolution and at the 

 same time has rendered much more difficult the task of un- 

 ravelling the past history of the true ferns. As soon as it was 

 demonstrated that many familiar Palaeozoic "ferns" are not 



1 Hudson (92) p. 29. ^ Hardy, Return of the Native, ii. p. 153. 



