REVISED LIST OF MARINE ALCLE. 143 



Plate IV. 



Fig. 1. Filaments of Urospora bangioides. (Nat. size.) 



Figs. 2, 3. Vegetative multiplication by pseudo-branch- 

 ing. X 350. 



Fig. 4. Base of filament. X 350. 



Fig. 5. Micro-zoosporangia and micro-zoospores. X 450. 



Fig. 6. Mega-zoosporangia and mega-zoospores. X 450. 



Fig. 7. Stages in the germination of a mega-zoospore. 

 X 350. 



Plate V. 



Figs. 1 — 5. Stages in the development of the peripheral 

 cells and mother-cell of sporangium of Pohjsi- 

 phonia fastig lata, seen from above. X 350. 



Fig. 6. Tetraspores in the act of escaping from the spor- 

 angium. X 350. 



Fig. 7. Transverse section of a frond at the level of ,a 

 sporangium shewing basal cell in connection 

 with three peripheral cells. X 450. 



Fig. 8. Longitudinal section of a frond, shewing the 

 arrangement of intercellular spaces and the 

 "plugs" closing the canals of communication 

 between the cells of the frond. X 350. 



Fig. 9. Isolated plugs, not yet closed by callus. X 450. 



