No. 544] 



BOTANICAL SOCIETY OF AMERICA 



219 



are eusporangiate, these paleozoic ferns were eusporan- 

 giate. And so we settled back comfortably to the convic- 

 tion that the paleozoic ferns were Marattiacese, repre- 

 sented to-day by a small tropical family ; that the euspo- 

 rangiate habit and synangia are historically older condi- 

 tions than the converse; and that the leptosporangiate 

 habit and sori of free sporangia are comparatively 

 modern. 



The change of view that modern paleobotany has intro- 

 duced must be familiar to most of you. The abundant 

 fern vegetation of the Paleozoic has vanished, having 

 been replaced by a great group of fern-like gymno- 

 sperms; many of the marattiaceous synangia have proved 

 to be the microsporangiate structures of these same gym- 

 nosperms; there is no indication that the eusporangiate 

 habit is older than the the leptosporangiate; and it is en- 

 tirely clear that our earliest known ferns had free spo- 

 rangia and not synangia. In fact, after the first revul- 

 sion of feeling, following the discovery of the fern-like 

 gymnosperms, the question was seriously raised, is there 

 any evidence of paleozoic ferns? Of course no one 

 doubted their existence, but where is the evidence? 



Paleobotany has now begun to answer this important 

 question. Evidence of the existence of a group of arbo- 

 rescent, Ma rattia-like ferns during the Upper Carbonifer- 

 ous is accumulating. Much of this evidence is negative, 

 for it consists simply of the fact that many species of cer- 

 tain of the large, so-called " frond genera" have not been 

 found to be fern-like gymnosperms. On the doctrine of 

 chance this may be worthy evidence. It simply means 

 that a vast display of fern-like leaves must contain some 

 ferns. The positive evidence, however, is su PP^ d b >' 



recently with the ^ 

 stems of the living : 

 is obvious. Moreov 

 one of the largest f 



