248 OSCILLATOKE^E. 



4. OSCILLATORIA TENUIS Ag. 



Plate LXXII. Fig. 1. 



Char. Stratum rich dark green, very thin, gelatinous, with 

 short rays. Filaments pale green, straight. Strise sub- 

 distant, evident. 



Grev. Edin., p. 303. ; Harv. in Hook. Brit. Flor. 374. ; 

 Harv. in Manual, p. 163. O. limosa Hook. Scot. ii. 

 p. 79. Conf. limosa Dillw. t. 20. O. viridis Johnst. 

 Berw. Flor. p. 264. 



Hob. Common in ditches. 



" In muddy ditches, at first resting at the bottom, but gra- 

 dually rising in bullated strata to the surface, common; stratum 

 extensive, glossy when dry, in which state it fully preserves 

 its colour. Filaments, of half the diameter of those of O. li- 

 mosa, pale green; striae distant and indistinct. It adheres 

 strongly to paper." Harv. The stratum of this species 

 exactly resembles that of O. limosa, and the filaments, like it 

 also, contract somewhat in drying ; they are, however, two 

 or three times smaller; the striae more distant, and not so 

 strongly marked. 



5. OSCILLATORIA CYANEA Ag. 



Char. " Glaucous blue. Filaments simple, entangled, cylin- 

 drical, even, with a deciduous coat. Joints obsolete, about 

 as long as broad. n Sm. 



Harv. Hook. Br. Fl. p. 374. Conferva cyanea, E. B. 

 t. 2578. ; Harv. Manual, p. 163. 



Hob. Damp walls on the inside of several Suffolk churches ; 

 at Icklingham and Hengrave ; also in Lincolnshire : Sir 

 Thomas Gage, Bart. 



" On the wall it is conspicuous for its light sky-blue colour, 

 like some sort of mucor. Under a high magnifier, and 

 when moistened, it is found to consist of minute, even, simple, 

 entangled threads, one five hundredth part of an inch in dia- 



