EXPLANATIONS AND REFERENCES, 

 PLATE CLXVIII. 



PAGE. 

 Figs. 1, 2 CALOTHRIX ORSINIANA, two filaments, .... 236 



" 3, 4. CALOTHRIX DILLWYNII, ..... 237 

 Fig. 5. CALOTHRIX GYPSOPHYLA, ..... 237 



Figs. 6, 7. " " smaller form, 237 



