128 Puget Sound Marine Sta. Pub. Vol. 1, No. 12 



PLATE 21 



19. Pith-filament; (a) characteristic ending of a frond filament. X75. 



20. Upper end of a pith-filament. X75. 



21. Utricle with unusual attachment; the result of a number of pith-fila- 

 ments growing up from the base. X75. 



22. Terminal and adjacent utricles. X75. 



23. Typical utricle branching from a filament with plug near base on 

 upper side. X75. 



