Brighton, on a plank between high and low water mark, Mr. Borrer ; 
Rocks by the Sea, Penzance, Mr. Ralfs. 
Georg. Distr. Coast of France. 
Descr. Stratum of indefinite extent, firm, membranaceous or coriaceous, peeling 
off in large flakes, without much lubricity, and without gloss when dry, of 
a dark green when growing above high-water mark, and a blueish green 
when submerged. Filaments slender, densely interwoven together, twisted 
like the letter S, or like a corkscrew, radiating in all directions. 
The specimens from the South of England are of a much 
brighter colour, and the stratum thinner than in the original 
Scotch specimens, but the microscopic character is very similar. 
Whether the O. subsalsa of Agardh be different, | am unable to say. 
B. Fig. 1. OsciLLaroRIA SPIRALIS; part of a stratum :—of the natural size. 
2. Filaments :—highly magnified. 
Puats CV. C. 
SPIRULINA TENUISSIMA, Kz. 
Gen. Cuar. Pilaments lymg in a mucous layer, rigid, simple, spirally 
twisted, vividly oscillating. Zuée continuous; endochrome green, 
more or less distinctly annulated.—Sprrutina (Zurp.). a diminutive 
of spira, a twist or curl. 
Sprrutina fenuissima; “stratum very lubricous, eruginous, subradiant ; 
filaments densely spiral, very slender, parallel, flexuous ”. 
SpiRULINA tenuissima, Avitz. Phyc. Gen. p. 183. Ralfs, in Ann. Nat. Hist. 
vol. xvi. p. 309. Pl. 10. 
Has. On decaying A/ge@ in a brackish pool near the Menai Bridge, and on 
sticks in brackish pools at Penman Pool near Dolgelly, Mr. Ralfs. 
Aberdeen, Dr. Dickie. 
Grocer. Distr. Europe. 
Descr. “It forms at first a thin pellicle of a rich green colour, but in an ad- 
vanced state becomes somewhat skin-like and tinged with brown; the filaments 
are extremely slender, of a pale blueish green colour, elongated, straight 
when free, equal, not attenuated at the extremities, vividly oscillating. 
Spires very close, like the volutions of some shells, broader than long. 
There is no appearance of granular matter, and the filaments are so fine 
that I cannot ascertain whether they are jomted”. Ralfs. 7. c. 
PPR AAP 
Having never seen this plant in a living state, I prefer giving 
Mr. Ralfs’ excellent description in his own words. I am indebted 
to Dr. Dickie for beautiful dried specimens, from one of which 
my figure has been taken. 
C. Fig. 1. Sprrutina TENUISSIMA, part of the stratum :—of the natural size. 
2. Filaments, :—highly magnified. 
