Plate XIII. 



Figs. 1-6. Sanjassmn énerve Ac. 



1. a. Middle portion of a fertile frond, siiowing a characteristic 

 lateral branch, h, cross sections of the principal stem, c, a 

 typical leaf on the lateral branches. 



2. A fertile lateral branch from the U[)[)er portion of the same 

 individual as shown in fig. 1. 



3. a, h, Eeceptacnlar rannilets. In b, a receptacle bears a minor 

 receptacle accompanied with a bractlet. 



4. Terminal portion of a full-grown sterile frond. 



5. A typical, young lateral branch of the same. 



f). Lower portion of the same frond, with a cross-section. 

 Figs. 7-17. Sargassum Jiemiphyllum Ag. 



7. Basal portion of a frond with symmetrical leaves. 



8. Middle portion of the same frond, with lateral branclu-s, two of 

 the fulcrant leaves still riMiiaining attached. 



0. A young lateral branch, ca. x 3. 



10. Insertion point of a full-grown lateral branch. 



11. Vesicles with a flat, short crown leaflet. X 2, 



12. A ^ receptacular ramulet of the form ty[)ical of the species. 

 ca. X 3. 



13. A receptacular ramulet from a south-sea form. 



14. Basal portion of a frond with hemiphyllous basal leaves. 



15. A lateral branch in the upper part of the same. 



16. Large fulcrant leaves on well-develo[)ed sterile fronds, 



17. Marginated vesicles. 



Figs. 18-20. Sargassum Julvellmti Ag. 



18. Basal part of a well-grown fertile plant, with cross-sections of 

 the stems. 



19. U[)per portion of a branch of the plant illustrated in fig, 18; 

 the lower end marked with x is to be connected to the upper 

 end with the same mark in fig, 18, In this branch the recep- 

 tacles are not yet fully mature. 



20. Terminal portion of a branchlet with J receptacles, ca, x 2, 



