236 NEMATOGENE. 
late as the 27th September, but on October 7th all had disappeared. In 
the following year the Alga was seen first on the 3rd of July, and last 
on the 23rd of September. ‘ 
“The specimens obtained were invariably of similar breadth, and 
rarely presented more than four spiral turns, and when of this size were 
1-50th of an inch in length. The species at first, when mingling with 
the water, is of a dark green colour, when in calm weather it ascends to 
the surface in separate particles it appears pale green; when it does so 
en masse (the earliest symptoms of decay) it is of a pale blue, and in the 
last stage of decomposition ferrnginous. When two of the spiral 
portions come in contact they have an elastic power, by which they can, 
though slowly, disentangle themselves, and separate from each other.” 
Anabaena variabilis. Kutz. Phyc. Gen. 
Gelatinous, submembranaceous, deep blue-green. Trichomes 
slightly flexuously curved, almost parallel, verdigris green, joints 
globose or elliptic, compressed or depressedly subcylindrical, 
1-14 times longer than broad; heterocysts intercalated, paler ; 
spores numerous, seriate, ellipsoid, golden tawny, with a rather 
thick membrane. 
Size. Cells -0035--004 mm. ; heterocysts ‘007 mm.; spores 
‘00801 x -012 mm. 
Spherozyga Thwaitesti, Harv. Phyc. Britt. +. 118, B. 
Spherozyga variabilis, Kutz. Tab. Phyc. i., t. 96, Rabh. Alg. 
Eur. ii., 193. 
Trichormus rectus, Ralfs Ann. Nat. Hist. (1850) t. 8, f. 6. 
Anabaena licheniformis, Hass. Alg. 82, t. 75, f. 4? 
Trichormus Thwaitesti, Ralfs Ann. Nat. Hist. (1850) p. 
329, t. 8, f. 4. 
In ditches. 
It forms thin gelatinous dark green patches either on the damp soil 
covered at springtides, or at the bottom of brackish ditches and pools. 
Plate XCIILI. fig.2. Trichomes X 400, with heterocysts and spores. 
Anabaena Hassallii. Nord. and Witir. Alge Exs. 
Trichomes equal, curved, often circinate, interwoven in a thin 
blue-green stratum, joints globose or more or less compressed, 
delicately granular; heterocysts spherical, colourless, interca- 
lated without order ; spores oblong cylindrical, single or in pairs, 
distinctly curved, dark blue green, densely granulated, 14-23 
times as long as broad. 
Sizz. Cells ‘008 mm.; heterocysts -009--01 mm.; spores 
7012 x 025 mm. 
Spherozyga Hassallit, Rabh. Alg. Eur. ii., 195. 
Anubaena flos-aque, Hass. Alg. 282, t. 75, f. 2, Harv. Man. 
p- 186. 
: Dolichospermum Thompsoni, Ann, Nat. Hist. (1850), t. 9, 
. 3. 
