The English flora - SeaweedAfrica

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376 ALG^S CONFERVOIDEiE. [Oscillatorin.
In pools, along the muddy sea-shore, flooded by spring-tides. Appin,
Copt. CarmichaeL—'? Stratum exceedingly thin, slimy, bullated by the
extrication of air-bubbles, of a dark-green colour, spreading to an inde-
finite extent over the muddy bottom of the pool. Filaments 1— 2 lines
in length, much thicker than those of O. nigra, straight or slightly
curved, radiating very irregularly and generally in twisted bundles.
Stria? strongly marked, at intervals of about one-third the diameter of
the filament." Carm. MSS.—Mostly allied to O. limosa. In a dry
state, it is membranaceous, and scarcely adheres to paper.
14. O. subsdlsa, Ag. ? (submarine Oscillatoria); stratum
membranaceous seruginose-green smooth, filaments slender
densely interwoven, strise distant indistinct. Ag. Syst. Alg.
p. 66?
At Brighton, " on a plank, between high and low-water mark," Mr.
Borrer.—Stratum aeruginose or bluish-green, smooth, without gloss,
when dry, peeling off in membranaceous flakes ; filaments hyaline, slender,
densely packed, either straight or curved; strice not very evident.
In habit, it somewhat resembles O. lit toralis ; but the filaments are much
slenderer, and the stratum more membranaceous.
*** Nigrescentes. Stratum of a dull indistinct green, or inclin-
ing to purple, black or brown.
15. O. nigra, Vauch. (blackish Oscillatoria); stratum blackish-green
(when dry bluish-black) with long radii, filaments
pale bluish-green thick, strise very distinct and close. Hook.
Scot. P. II. p. 79. Ag. Syst. Alg. p. 63.— Conferva fontinalis,
Dilliv. Conf. t. 64.— O. limosa, Grev. Fl. Edin. p. 303,
(not of Ag.)
Ditches and ponds, common. Stratum extensive, blackish with a
shade of green, when dry blue-black, very rapid in its growth and sending
out long, vividly oscillating rays. Dillwyn's figure of Confervafontinalis
answers this species pretty correctly; but his description seems to
take in many others.
16. O. autumndlis, Ag. (autumnal Wall Oscillatoria'); stratum
purplish or greenish-black very lubricous shortly radiating, filaments
pale bluish-green, strise subdistant Ag. Syst. Alg. p. 62.
Lyngb. Hydroph. Dan. p. 95. Grev. Fl. Edin. p. 305.
On damp walls, abundant in autumn and winter. Stratum extensively
spreading, very dark and lubricous, glossy when dry; fdaments remarkably
pale ; striae not very evident.
17. O. contexta, Carm. (satin-like Oscillatoria); stratum
glossy black strongly striated, filaments thickish pale-green,
strise subdistant.
On moist ground; Appin, Capt. CarmichaeL—" Stratum of indefinite
extent, three feet and upwards, exceedingly thin and peeling off in large
flakes in dry weather, of a deep but shining black colour, scored or
striated in all directions. These striae are caused by thick fasciculi of
filaments, shooting out either parallel to or across each other, changing
their course from time to time, and sending off lateral fasciculi. The
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