916 



VII. ISOETB^. 



/. setacea. 



Vertical section of a 



sporangium, enclosing 



antheridia (mag.)* 



Jsoetis setacea. 



Phyllopode with double 

 ligule, sporangium con- 

 taining antheridia. 



Isoeies. Transverse seofcion of rhizome. 



Isoetes. Transverse section of the bases of 



fironds, showing the arrangement of the 



S and 9 sporangia (mag.). 



/. setacea. 



Transverse section of a sporangium, 



enclosing antheridia (mag.). 



/. lacustris. 

 Ligule (mag.). 



/, setacea. Macrospores (mag.). Jsoeles. Microspores (mag.). 





V 



si. 



/ 



\>^ 



"*^l^ 



/. lacustris, 

 9 phyllopode, showing the 

 young sporangium and 

 the ligule. 



/. lacustris, 



9 phyllopode, showing the 



sporangium open and 



deprived of spores. 



