3S 2 



STUDIES IN FOSSIL BOTANY 



Simp Lie es - 



FILICES — Isosporeae 



EUSPORANGIA TE. 



\ 



Gradatae 



MlXTAE 



Marattiaceae. 



Osmundaceae. 



Schizaeaceae. 



Gleicheniaceae. 



Matonineae. 



Loxsomaceae. 

 Hymenophyllaceae. 

 Cyatheaceae. 

 Dicksonieae (with some 



exceptions). 

 Dennstaedtiinae. 



Davallieae (with some 



exceptions). 

 Lindsayeae. 

 Pterideae and other Poly 



podiaceae. 



Leptosporangia te. 



1 



The Simplices are those Ferns in which all the 

 sporangia of a sorus are produced simultaneously, the 

 Gradatae those in which there is a definite succession 

 in time and space, the Mixtae those in which there is 

 a succession in time, but no regular succession in space. 



Other characters of importance coincide more or 

 less with the above ; for example, the sporangia tend 

 to become smaller, with fewer spores in each, as we 

 advance from the Simplices to the Mixtae. 



It will be seen that the geological evidence, so far 

 as it goes, harmonises well, on the whole, with the 

 main divisions in Professor Bower's system. The 

 old distinction between Eusporangiatae and Lepto- 



