374 ALGM CONFER VOIDED. [Oscillatoria. 



" The irregularity of its appearance arises from the filaments being collect- 

 ed together into little- ascending tufts, apparently rooted in the muddy 

 deposit of the water. Each tuft proves, on examination, to consist of 

 simple, uniform, even filaments, crowded together and quite pellucid 

 and equally destitute of joints and branches ; their diameter is not more 

 than an eight or ten-thousandth part of an inch." Sm. 



** Virescentes. Stratum of an ceruginose or blue-green colour. 



5. 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 Ag. Syst. Alg. p. 66. (not of Grev. Fl. Edin. p. 303, 



nor Hook. Scot. P. II. p. 79 ) 



Ditches and pools.— Stratum of very rapid growth and intensely 

 rich dark-green colour, sending out long radii, equally or in bundles, 

 of scarcely a paler hue than the stratum. Filaments thicker than in 

 any other British species, bluish-green (under the microscope) vividly 

 oscillating.— This fine species is apparently alluded toby Dilhvyn, in his 

 description of Conferva fontinalis, t. 6 i ; but the figure is more like O. 

 nigra. In drying, it adheres closely to paper. From O. major, it differs 

 in the much greater diameter of its filaments, and darker colour; and 

 from O.jirinceps (apparently), in the smaller size and brighter colour. It 

 is therefore intermediate between these species. 



6. 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. — Ag. Syst. 

 Alg. p. 65. Grev. Fl. Edin. p. 303 — O. limosa, Hook. Scot. 

 P. II. p. 79. — Conferva limosa, Dillw. Conf. t. 20. — O. viridis, 

 Johnst. Berw. Fl. p. 264. 



In muddy ditches, at first resting on the bottom ; but gradually ris- 

 ing in bullated strata to the surface; common— Stratum extensive, glossy 

 when dry, in which state it fully preserves its colour. Filaments^ half 

 the diameter of those of O. limosa, pale-green ; striae distant and indis- 

 tinct. It adheres strongly to paper. 



7. O. cydnea, Ag. (bluish Oscillatoria); glaucous-blue, fila- 

 ments simple entangled cylindrical even with a deciduous coat, 

 joints obsolete about as broad as long. Sm. — Ag. Syst. Alg. 

 p. 68. E. Bot. t. 2578. 



Damp walls on the inside of several Suffolk churches, as Icklingharn 

 and Hengrave ; also in Lancashire, 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 500dth part of 

 an inch in diameter, coated with a frequently interrupted covering, of a 

 dull glaucous-green hue, under which the thread itself appears of a 

 lighter glaucous-bluish colour, very even in thickness and surface, con- 

 sisting of scarcely distinguishable joints, about as broad as they are long." 

 Sm. 



8. O. splendida, Grev. (bright-green Oscillatoria); stratum 

 bright seruginose or blue-green thin with short rays, filaments 



