OSCILLATOKIACEiE. 
103 
Strata varying in extent, lying on the surface of mud, or floating, or entangled with 
other Algas and attached to them, of a very dull, blackish, or somewhat violet colour, 
with shades of seruginous green. Filaments scarcely more than half the diameter of 
those of L. ferruginea ; with thin, membranous cell-walls, and densely annulated, dark 
or dull coloured endochrome. When dry the stratum becomes brittle, and frequently 
breaks off from the paper in flakes. 
Plate XLVII. D. Fig. 1 . Lyngbya nigrescens , the natural size. Fig. 2. Portion of 
a filament, magnified. Fig. 3. Section of the same, more highly magnified. 
5. Lyngbya confervoides , A g. ; filaments very slender, flaccid, elongate, forming long, 
comose fasciculi, floating freely from a blackish green basal stratum ; annuli not very 
strongly marked. Ag. Syst. p. 73. Kiitz. Sp. Alg. p. 285. (Tab. XLVII. C.) 
Hab. Sea-shores, Charleston, S. Carolina, Professor Lewis E. Gibbes. (v. s.) 
Stratum dark, olivaceous, or blackish green, emitting long bundles of slender filaments, 
1-2 inches long, which float freely in the water. Filaments lying parallel in the 
bundles, flexuous, but scarcely interwoven and often separate ; with very thin, narrow, 
membranous tubes, and a dense, dull-green endochrome, which is much less distinctly 
annulated than in L. ferruginea. The diameter of the filament is also much less than 
in that species. 
I have compared the above quoted species with an authentic one from Professor 
J. Agardh, and find little difference between them. 
Plate. XLVII. C. Fig. 1 . Lyngbya confervoides , the natural size. Fig. 2. Portion 
of two filaments, magnified. Fig. 3. Section, more highly magnified. 
6. Lyngbya pusilla , Harv. ; stratum minute, blackish-green ; filaments very slender, 
short, crisped, spreading in small bundles ; endochrome pale, dull-green, annulate, cell- 
wall very thin. (Tab. XLVII. E.) 
Hab. Parasitic on small Algrn, at Sullivan’s Island, S.C., W. H. H. (v. v.) 
This spreads over small Algae in thin strata, composed of densely matted filaments, 
and emitting to all sides free, fascicled filaments. These latter are about quarter of an 
inch long, and half the diameter of those of L. ferruginea, with a pale endochrome. The 
cell-wall is extremely thin ; the endochrome' quite fills the tube, leaving a scarcely per- 
ceptible margin. The annuli are tolerably definite. 
Possibly this may be an Oscillatoria . 
Plate XLVII. E. Fig. 1 . Lyngbya pusilla , the natural size. Fig 2. Portions of 
three filaments, magnified. Fig. 3. Section of a filament, highly magnified. 
