♦ , I
!* • :
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 fonr spiral turns, and when of this size were
l-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 ferruginous. 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 v a r ia h ilis. Kntz. Phyc. Oen.
Gelatinous, submembranaoeous, deep blue-green. Triobomes
slightly flexuously curved, almost parallel, verdigris green, joints
globose or elliptic, compressed or depressedly subcylindrical,
1 - 1 -^ times longer tban broad ; lieterocysts intercalated, paler ;
spores numerous, seriate, ellipsoid, golden tawny, witb a ratber
thick membrane.
Siz e . Cells -0035--004 mm. ; h ete ro cy sts -007 mm. ; spores
•00801 X •012 mm.
Splicerozyga Thwaitesii, Harv. Phyc. Britt, t. 113, B.
Sphærozyga variahilis, Kutz. Tab. Phyc. i., t. 96, Eabh. Alg.
Eur. ii., 193.
Trichormus rectus, Ralfs Ann. Na t. Hist. (1850) t. 8 ,f. 6.
Anahaena licheniformis, Hass. Alg. 82, t. 75, f. 4 ?
Trichoimncs Thwaitesii, Ralfs Ann. Nat. Hist. (1850) p.
329, t. 8, f. 4.
In ditches.
I t forms thin gelatinous dark green patches either on the damp soil
covered at springtides, or at the bottom of brackish ditches and pools.
Plate X C III. fig. 2. Trichomes X 400, with heterooysts and spores.
Anabaena H a s s a llii. Nord, and Wittr. Algæ Exs.
Trichomes equal, curved, often circinate, interwoven in a thin
blue-green stratum, joints globose or more or less compressed,
delicately granular ; heterocysts sphærical, colourless, intercalated
without order ; spores oblong cylindrical, single or in pairs,
distinctly curved, dark blue green, densely granulated, 1 ^ -2 ^
times as long as broad.
S iz e . Cells -008 mm. ; heterocysts -009--01 mm. ; spores
•012 X 025 mm.
Sphærozyga Hassallii, Eabb. Alg. Eur. ii., 195.
Anahaena flos-aquoe, Hass. Alg. 282, t. 75, f. 2, Harv. Man.
p. 186.
Dolichospermum Thompsoni, Ann. Nat. Hist. (1850), t. 9,
f. 3.
Anabaena circinalis, Phillips in Grevillea ix., p. 4, t. 134,
figs- « ,/, g-
In ditches with Confervæ, and floating on lakes.
“ Floating like powdered verdigris on mountain lochs.” This speoies
seems to be variable in the form and size of the spores, and in the number
of vegetative cells which occur between the heterocysts and spores.
Wittrock has figured varieties in which two, or even sometimes one,
cell intervenes between the heterocyst and spore, alluding to the fact
that in English specimens they are sometimes in juxtaposition. Although
technically the Shropshire specimens would seem to belong to
Sphærozyga, yet in all other features they agree so well with this species
that we have cited them here as abnormal forms of the present speoies.
Plate X C l l l . fig. 3. Portions of trichomes with heterooysts and
spores X 400 ; b, after Balfs ; c, after Phillips.
A nabaena R a lfs ii. (Kutz.)
Forming extensive strata of a velvety ricb dark green colour,
sometimes verging towards verdigris green.
Triobomes moniliform, joints sphærioal. Heterocysts elliptical,
spores elliptic or cylindrical, one or two in each series
not contiguous to tbe heterocysts.
S iz e . Cells -004 mm. diam. Heterooysts -005--006 x 008
mm. Spores -008--01 x -022--03 mm.
Sphærozyga Ra lfsii (Tbw.) Eabh. Alg. Eur. ii., 193. Kirch.
Alg. Scbl. 287.
Dolichospermum Ralfsii, Ann. Nat. His. 1850, t. 9, f. 2.
Cylindrospermum Ealfsii, Kutz. Tab. Phyc. t. 98, f. 7.
In bogs and rivulets.
“ Distinguished from A . inæqualis by its elliptical heterccysts (which
are comparatively less broad), by its more orbicular ordinary joints, and
by having fewer spores.”—Ralfs.
Plate X C IV . fig. 1. Trichomes with heterooysts and spores X 400
diam.
Anab a en a Sm ith ii. (flhwi) Nord. ^ Wittr. Alg. Exs. No. 197.
Trichomes straight, each included in a definite gelatinons
sheath ; joints subsphærical, compressed, about as long as wide ;
lieterocysts subsphærical somewhat barrel shaped, balf as wide
again as the joints, puncta very distinct ; spores cylindrical, very
unequal in length, with th e ends rounded and somewhat tru n cate.
S iz e . Cells-004--006 mm. diam. Heterocysts-008--009 x
•009--013 mm. Spores -009--012 x -02--04 mm. (Wittrock.)
Dolichospermum Smithii, Thwaites Ann. Nat. Hist. 1850, t. 9,
f. 4.
In boggy pools witb other Algæ.