MARINE ALGiE. 85 

 CIV. MlCROCOLEUS. 



Filaments minute, rigid, straight, several enclosed 

 together in a membranous sheath. 



1. Microcoleus anguiformis. 



CV. OSCILLATORIA. 



Filaments needle-shaped, straight or slightly curved, 

 short. Named from the curious motion observed in 

 the filaments, which resembles the oscillations of a pen- 

 dulum. 



1 . Oscillatoria littoralis. 



2. „ subsalsa. 



3. „ spiralis, 



4. „ nigro-viridis. 



5. „ subuliformis. 



6. „ insignis. 



CVI. Spirulina. 



Filaments spirally twisted, lying in a mucous stratum, 

 vividly oscillating. 



1 , Spirulina tenuissima. 



2. „ Hutchinsise. 



