PLATE XXVI. 



A. RIVULAKIA, page 222. 



Fig, 1, R. atra, on a stone ; the natural size. 2, ver- 

 tical section of a frond. 3, filament from the same ; 

 magnified. 



B. SCHIZOTHRTX, page 223. 



Fig. 1, S. Cresswellii, on a stone; the natural size. 

 2, filaments from the same ; magnified. 3, portion 

 of a filament ; very highly magnified. 



C. CALOTHRIX, page 223. 



Fig. 1, C. confervicola, growing on Ceramium rubrum ; 

 the natural size. 2, filaments from the same ; mag- 

 nified. 3, small fragment of a filament ; highly 

 magnified. 



D. MICROCOLEUS, page 227. 



Fig. 1, M. anguiformis ; the natural size. 2, a sheath ; 

 magnified. 3, filament from the same ; highly mag- 

 nified. 



E. LYNGBYA, page 225. 



Fig. 1, L. majuscula ; the natural size. 2, portion of 

 a filament ; magnified. 



F. OSCILLATORIA, page 228. 



Fig. 1, stratum of O. insignis, as it appears to the eye. 



2, filament of the same species ; highly magnified. 



3, filament of O. nigro-viridis ; magnified. 



