EXPLANATIONS AND REFERENCES, 

 PLATE CLXXI. 



PAGE. 

 Fig. 1-4. MASTTGONEMA AERUGINEUM, a distinct mode of fruiting, the 



basal cells developing macro- 

 gonidia; from Florida, . 242 



Figs. 5, 6. Filaments from a floating mass; basal heterocysts torn off; 



brownish color, ..... 242 



Fig. 7. Ordinary condition of Florida specimens, . . . 242 



Figs. 8, 9. Three branching forms from a gelatinous coating on the sides of 



a pump trough, ...... 241 



