246 NEMATOGENE. 
Spirulina oscillarioides. Turp. 
Solitary, or forming little green tufts, sometimes almost 
radiating. Trichomes more or less elongated, nearly erect, pale 
blue green, twisted in lax or dense spirals, endowed with active 
motion. 
S1ze.—Trichomes :0015--002 mm. diam. 
Kutz. Tab. Phyc. i, t. 37, f. 8. Rabh. Alg, Eur. ii, 91. 
Kirch, Alg. Schl. p. 250. Cohn Nova Acta xxiv., t. 15, f. 
15. 
var, b, minutissima. FRabh, Aly. Eur. u., 91. 
Trichomes abbreviated, more loosely spiral. 
Spirillum minutissimum, Hass. Alg. 278, t. 75, f, 8. 
Spirulina brevis, Kutz. Tab. Phyc. i., ¢. 37, f. 9. 
In fresh, brackish, or thermal waters. 
Plate XCVI. fig. 3. Portions of trichomes X 400. Fragment 
further magnified. 
Spirulina tenuissima. Kutz. Spec. Alg. 236. 
Forming a membranaceous, lubricous, dark blue green floating 
stratum, trichomes very thin, flexuous, very densely spiral, en- 
dowed with active motion ; joints very indistinct. 
Size.—Trichomes very thin. Spirals -005 mm. diam. 
Rabh. Alg. Eur. ii., 92. Harv. Phyc. Britt. t. 105, f. ¢. 
In brackish ditches. 
Floating in Jarge blue green masses on the surface of brackish ditches. 
The threads are too delicate for measurement, and appear only as lines 
under a magnifying power of 400 diameters. 
Plate XCVI. fig. 2. Portions of trichomes X 400. 
Genus 101, OSCILLARIA. Bosc. (1800.) 
Trichomes simple, usually distinctly articulate, rigid, straight, 
or a little curved, rarely circinate or spirally convolute, for the 
most part brightly coloured (blue-green, steel-blue, violet, 
ceruginous, &c.), motile, nestling in a matrical mucilage; joints 
disc-shaped in the front view, without a sheath distinct from 
the trichome. 
Consult Dr. d’Alquen in Quart. Journ. Mier. Sci. iv. (1856), p. 245. 
The species are at present distinguished by very artificial characters, 
which are by no means permanent, in which respect the genus is not in a 
much better condition than it was forty years ago. 
