EXPLANATIONS AND REFERENCES, 

 PLATE CLXIX. 



PAGE. 

 Figs. 1, 2. CALOTHRIX HOSFORDII, a filament with numerous young forms 



attached, .... 239 



" 3, 4. Three young plants, isolated, ..... 239 

 Fig. 5-7. CALOTHRIX BREBISSONH, two characteristic plants, . 238 



