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ments beautifully granulated, extreme apex broadly rounded, or
somewhat beaked, cell-contents homogenous or delicately
granular.
S i z e . Threads 'OOTe-'Ol m m .
Kutz. Tab. Phyc. i., t. 42, f. 4. Rabh. Alg. Eur. ii., 107.
On wet rocks, walls, or overrunning mosses.
The variety “ subsalsa,” bearded,at the apex, was found on Greenwich
Pier in 18C1.
Plate XCFII. fig 6. Portions of trichomes X 400.
Oscillazia nigza. Vauch. Oonf. 192, t. 15, /. 4.
Stratum more or less compact, somewhat membranaceous,
often floating, steel-blue, or dark olive nearly black, with radii
more or less elongated, of tbe same colour. Trichomes straight
or slightly flexuous, obtusely rounded at the apex, or attenuated,
and sometimes bearded ; joints equal in length to their diameter
(after division one half or one third as long) ; dissepiments very
distinctly granulated, apiculus often straight, somewhat rostellate
and bearded, rarely slightly curved ; cell-contents pale olive,
finely granular.
S i z e . Threads ’OOQ-'Ol mm. diam.
Rabh. Alg. Eur. i., 107. Kiroh. Alg. Schl. 247. Harv.
Man. 165. Eng. Fl. v., 376. Eng. Bot. t. 2527.
Oscillatoria nigra, Hass. Alg. 255, t. 71, f. 3. Hook. El.
Soot. 79. Jenn. Tunb. Wells 188. Mack. Hib. 289. Gray
Arr. i., 281.
Conferva fontinalis, Dillw. Conf. t. 64. Huds. El. Ang.
592. Lightf. Fl. Scot. 976. With. Arr. iv., 128.
In ditches and ponds. ^
“ Stratum extensive, blackish, with a shade of green, when dry bine-
black, very rapid in its growth, and sending out long, vividly oscillating
rays.”—llarvey.
Plate XOVII. fig. 6. Portions of trichomes X 400.
Oscillazia nigzo-viz idls. Thwaites in Harv. Phyo.
Stratum thin, of a dark olive green, almost black, growing
upon the mud, and subsequently floating in large masses.
Trichomes pale dull green, with obtuse, distinctly curved,
scarcely attenuated apices ; joints indistinct, about half as long
as broad, cell-contents slightly granulose.
S i z e . Trichomes -012 mm. diam.
Harv. Phyc. Britt, t. 251 a . Eabh. Alg. Eur. ii.. 292.
In brackish ditches. August.
Plate X C Y IIl. fig. 2. Trichomes of O. nigro-viridis X 400 diam.
Osc illazia chalyb ea . Mertens, in Jurgens Algce.
Floating. Stratum broadly expanded, with long radii, dark
blue green or steel-blue, shining ; triobomes pale steel-blue,
slightly flexuous, a little attenuated at the apex, joints three or
four times shorter than tbeir diameter, a little contracted at the
dissepiments, which are not granulated, apiculus slightly curved,
obtusely rounded, now and then rostellate, cell-oontents pale
steel-blue, granular.
S iz e . Threads 'OOflS-'Ol mm. diam.
Ku tz . Tab. Phyo. i., t. 40, f. 8 . Rabh. Alg. Eur. ii., 108.
In still and stagnant water.
The specimens figured were collected from a tank in one of the stoves
of the Royal Botanic Gardens, Regent’s Park.
Plate XOV H I . Jig. 1. Trichomes of 0. X 400 diam.
Osc illazia F zo lich ii. KuU. Phye. Gen. 189.
Stratum dark steel-blue, or a t first olive, then dark blue,
often elongated, radiating, opaque, shining ; trichomes nearly
equal, straight ; joints 2, 3, or 4 times shorter than their
diameter, with a double series of granular points more or less
dense at the junction, often confluent, so as to resemble a single
series ; apiculus broadly rounded, straight, or declined; cell-
contents blue, becoming steel-blue, homogenous.
S i z e . Threads ■015--018 mm. diam.
Kutz. Tab. Phyc. i., t. 43, f. 1. Rabh. Alg. Eur. ii., 109.
Oscillatoria mucosa, Hass. Alg. 247, t. 71, f. 1.
In ditches, pools, and boggy places, sometimes amongst
mosses.
The finest of the species yet detected in Britain.
Plate XOVII. f. 7. Portions of trichomes X 400.
Osc illa z ia in s ig n is . Thwaites in Phyc. Britt.
Stratum thin, covering decayed vegetable matter at the
bottom of a ditch, with a dark-brown coating, becoming somewhat
greenish in drying ; trichomes very large, rather brittle,
their apices rounded, somewhat oblique, and furnished with
numerous motionless cilia ; cell-contents distinctly granulose.
S iz e . Trichomes '018 mm. with sheath.
Rabh. Alg. Eur. ii., 293. Harv. Phyc. Brit, ii., t. 251, f. c.
In a brackish ditch. November.