228 PLANT-LIFE 



the alleged dominance of Ferns in the Palaeozoic Flora 

 has no foundation in fact. It has been demonstrated 

 that a large part of the Fernlike forms found as fossils 

 are the vestiges of seed-bearing plants, now known as 

 Pteridosperms (Seed-Ferns). The student of fossil 

 plants has now to be exceedingly careful in forming 

 conclusions in regard to alleged fossil Ferns, for unless 

 the distinctive evidence of sporangia, showing a true 

 Fern character, is present, identification is difficult, and 

 it is easy to go astray. But if Feriis were not dominant 

 in Palaeozoic times, it is certain they were well repre- 

 sented. There then existed a group, the Botryopteridese, 

 all the species of which are extinct, and which differed 

 greatly from modern forms; yet it would seem that in 

 their own day and generation they were the leading 

 Fern group. The external characteristics of the group 

 can hardly be decided, but the anatomy of their stems 

 reveals a feature peculiar to all the species. The stems 

 and leaf-stalks (petioles) were monostelic, which means 

 that they were traversed by a single central vascular 

 conducting cylinder. In this respect they differed from 

 the majority of modern Ferns (see Plate XXXIL). 



It was in the Carboniferous and the later Permian 

 Periods that the Botryopterideee flourished, and con- 

 temporaneous with them were the members of a second 

 group, the Marattiacese (see p. 155); but whereas the 

 former were exclusively Palaeozoic and probably prior 

 in appearance, the latter have representatives still 

 existing. But the few living species are not the same 

 as those which throve in Palaeozoic times, and the fossil 

 evidence goes to show that the group as a whole was 

 next in importance to the Botryopterideae in Palaeozoic 



