FERNS— FRONDS 269 



most commonly preserved) it is now impossible to say 

 whether a given Palaeozoic plant belonged to the true 

 Ferns or to the Fern-like Seed-plants. 



It is probable that the impressions of " Fern-fronds," 

 often preserved in such exquisite beauty in the strata 

 of the Coal-measures, are better known to the non- 

 botanical observer than any other specimens of fossil 

 plants. The character of such leaves has specially 

 lent itself to this mode of preservation, and as regards 

 form and venation, nothing more perfect could be desired 

 than many of the impressions from the Carboniferous 

 and other strata. 



Almost all the well-known genera of conspicuous 

 Fern-like fronds have now, however, fallen under suspicion. 

 In several of them the presence of seeds has been 

 actually demonstrated, in many others all the prob- 

 abilities point the same way, but there is good reason 

 to believe that some of these artificial form-genera 

 include true Ferns as well as Seed-plants of similar 

 habit. It will therefore be necessary, before going 

 further, to say something of the fronds hitherto attributed 

 to Ferns. 



1. Fronds. — Brongniart was the first to construct a 

 regular system of classification of the Fern-like plants, 

 based entirely on the form and venation of the leaf, 

 and since his time this system has been further 

 elaborated, so that any fossil " Fern-frond " can now 

 be referred to a provisional genus and species, according 

 to its conformation and the course of its veins. The 

 same system can be, and has been, applied to recent 

 Ferns, and has, of course, proved to be purely artificial. 



