n6 Plant Life and Evolution 



the pteridophytes in the Paleozoic flora is well 

 known. From the Devonian, where the first fern- 

 like remains are met with, they increase in impor- 

 tance, culminating in the Carboniferous. The rich- 

 ness of the Coal-flora in pteridophytes is sufficiently 

 familiar. It is now known that many of the sup- 

 posed Paleozoic ferns were really seed-bearing 

 plants which have very appropriately been named 

 " Pteridosperms " seed-ferns and some enthusi- 

 astic students of these plants have gone so far as 

 to doubt the presence of any true ferns during the 

 Paleozoic, a view which it is hardly necessary to 

 say is hardly likely to prove correct, unless we sup- 

 pose that these seed-ferns originated spontaneously 

 and had no ancestors. 



Distribution of Living Pteridophytes. It is usu- 

 ally taken for granted that the pteridophytes of the 

 present day are mere remnants of the rich Paleozoic 

 flora; but a study of the distribution of the existing 

 ferns shows that this is not the case. It is true 

 that the living horsetails are very degenerate de- 

 scendants of their Paleozoic ancestors, and the same 

 may be said to a lesser degree of the club-mosses. 

 The case of the true ferns, however, is quite dif- 

 ferent. The fern types characteristic of the earlier 

 geological epochs have largely disappeared, although 

 there are some ferns, especially in the tropics, which 

 have changed very little from their ancient fore- 

 bears. These ancient types have been largely re- 

 placed by ferns which are better adapted to modern 



