IX MARATTIACEA£—ISOETACEJ£ 301 



We may conclude, then, from the data at our disposal, 

 that the living;' eusporangiate FilicinejE consist of a few 

 remnants of widely divergent branches of a common stock, 

 which formerly was predominant, but has been supplanted by 

 more specialised modern types. From this primitive stock 

 have arisen on the one hand the leptosporangiate Ferns, on 

 the other, through Isoetes, or some similar heterosporous forms, 

 the Angiosperms. 



