Mr. J. Ralfs on the Nostochinez. 841 
is the true Flos-aque of almost every algologist prior to Lyngbye, 
whose error has misled many succeeding writers and confounded 
plants of widely different aspect. The descriptions of Linneus, 
Roth and Agardh, although more or less deficient, agree far 
better with this species than with any others which have been 
confused with it. Lyngbye, indeed, suspected that his Nostoc 
Flos-aque was distinct from the plant of the two latter writers*, 
an opinion confirmed by Agardh so far as regards himself. 
Mr. Borrer has sent me a specimen of Byssus Flos-aque distri- 
buted by Mohr, who, there is every reason to suppose, was fully 
acquainted with the plant then known by that name: the speci- 
men, which is a very good one, scarcely differs even in colour 
from those recently gathered by Professors Kiitzing and Allman. 
I cannot obtain the slightest clue to the Flos-aque of our earlier 
British writers. They give no habitats, and although the specific 
definition of Hudson, Lightfoot and Withering agrees with this 
species (“filamentis plumosis natantibus”), yet, as it is a mere copy 
from Linnzus, no dependence can be placed upon it. The two 
former authors give no original remarks, and Withering’s own 
observations agree but indifferently with his specific quotation ; for 
his description, “jointed filaments straight or curled like a cork- 
screw,” is more applicable to a Trichormus. 
PuaTE IX. fig. 6. a, portion of foreign specimen magnified; 6, Dub- 
lin sp. ditto; c, filaments highly magnified. 
2. A. cyaneum ( ). Filaments free, aggregated into a thin mucous 
stratum ; sporangia linear, eight to twelve times longer than broad, 
furnished with a conspicuous hyaline covering. Limnochlide Flos. 
aque, B. hercynica, Kitzing, Species Algarum, p. 286 (1849) ; 
Tabule Phycologice, t. 91. f. 11? 
On aquatic plants in boggy pools at Llyn Gwernan and Dolmelynlyn 
near Dolgelley, J. R. 
Germany, Kiitzing. 
Stratum minute, thin, tender, of an opake light blue colour. 
Filaments very slender, straight, nearly colourless, having a 
slightly dotted appearance from the scattered granular endo- 
chrome, not constricted at the dissepiments, which are very in- 
distinct, and only to be detected by careful examination in a 
favourable light ; ends obtuse, not attenuated. Joints or ordi- 
nary cells nearly equal in length and breadth. Sporangia elon- 
gated, cylindrical, generally solitary near the centre of each fila- 
ment, but sometimes scattered, each inclosed in a broad, hyaline 
covering. 
* “ An sit Conferva Flos-aque, Roth, Oscillatoria Flos-aque, Ag., justo 
amnbigitur ; ille enim filis rectis et parallelis gaudere describuntur, hee vero 
filis curvatis, implexis.instructa est.”’—Lyugbye, Tentamen Hydrophyto- 
logie Danicee, p. 202. 
