Plate XI. 



Pitrs. 1-7. Sargassum f^erratifolium. Ag. 



1. Tenninal portion of a well developed but sterile f'ronil. 



2. Basal portion of the same. 



3. Basal portion of a full-grown frond. 



4. Middle jwrtion of the same ; with a crosssection of the stem. 



i3. A typical lateral branch just belbre maturity ; with cross-sections 



of stems. 

 Ü. Basal region of a fertile lateral branch to show the receptacular 



ranndets. The lower ramulet has all its bractlets dropped off. 



With a cross-section of the stem. 

 7. A typical leaf. 



