304 STUDIES IN FOSSIL BOTANY 



The recent work of Rudolf on the anatomical 

 relations between Psaronius and the Marattiaceae has 

 on the whole confirmed the long-established view of 

 their affinity ; the common characters are to be found 

 chiefly in the course of the vascular strands and in the 

 structure of the roots, to which, as it now appears, the 

 endarchy of the steles in the stem may be added. The 

 evidence afforded by the Psaronius stems, taken in 

 conjunction with that derived from the synangic 

 fructifications, seems to leave little room for doubt that 

 true Ferns with Marattiaceous affinities formed an 

 important constituent of the Permo-carboniferous Flora, 

 especially towards the close of that period. Where 

 anatomical evidence is not available, it is, however, 

 extremely difficult to distinguish between true Ferns of 

 this group and plants more probably belonging to the 

 Pteridospermeae. 



