Oscittatoria ] ALQ^ CHLOROSPERMEJE. 23 9 



cicles of filaments. Harv. in Hook. Br. Fl. v. ii. p. 373. — 

 Scytonema Bangii, Lyngb. 



On mosses, in alpine situations. At Killarney. Stratum 2—3 

 inches broad. Filaments pale green, slender. 



2. O. chthonoplastes, HofFm. Sheathing Oscillatoria. Stra- 

 tum dull green ; filaments parallel, penicillating from the apex 

 of the decumbent, elongated, flexuose, sheath-like fascicles. 

 Harv. in Hooh. Br. Fl. v. ii. p. 373. — Conf. vaginata, E. Bot. 

 t. 1995. 



On the muddy sea-shores, or on naked soil by road-sides, &c. 



* * Virescentes; stratum of an airuginose or blue-green colour. 



3. O. limosa, Ag. Green Mud Oscillatoria. Stratum rich 

 dark-green,- glossy, gelatinous, with long rays ; filaments green, 

 thick, straight and rigid ; striae strongly marked and very 

 closely set. Harv. in Hooh. Br. Fl. v. ii. p. 374. 



Ditches and pools. 



4. O. tenuis, Ag. Lesser Mud Oscillatoria. Stratum rich 

 dark-green, very thin, gelatinous, with short rays; filaments 

 pale green, straight and rigid ; striae distant, not strongly 

 marked. Harv. in Hook. Br. Fl. v. ii/p. 374. — Conf. limosa, 

 Dillw. t. 20. 



In muddy ditches, first spreading over the mud ; finally rising in 

 scum-like strata to the surface. Filaments half the diameter of those of 

 O. limosa, and the stratum thinner. 



5. O. decorticans, Grev. Ribband Oscillatoria. Stratum 

 smooth, glaucous-green, membranaceous; filaments very slen- 

 der, curved, pale, bluish-green ; striae distant. Harv. in Hook. 

 Br. Fl. v. ii. p. 375. — Conf. decorticum, Dillw. t. 26. 



Damp walls, rotten timber, &c. 



# * * Nigrescent.es ; stratum of a dull indistinct green, or in- 



clining to purple, black or brown. 



6. O. nigra, Vauch. Blackish Oscillatoria. Stratum black- 

 ish-green (when dry bluish-black), with long radii ; filaments 

 pale bluish-green, thick; striae very distinct and close. Harv. 

 in Hook. Br. Fl. v. ii. p. 376.— Conf. fontinalis, Dillw. t. 64. 



Ditches and ponds, common. 



7. O. autumnalis, Ag. Aidumnal Wall Oscillatoria. Stra- 

 tum purplish or greenish black, very lubricous, shortly radiat- 

 ing ; filaments pale bluish green ; striae subdistant. Harv. in 

 Hook. Br. Fl. v. ii. p. 376. 



On damp walls, very common in autumn and winter. 



