246 NEMATOGKNJL. 



Spixulina oscillaxioides. Tt/rp. 



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 witli active 

 motion. 



SIZE. Trichomes -0015--002 mm. diam. 



Kutz. Tab. Phyc. i., t. 37, f. 8. Rabli. Alg. Eur. ii., 91. 

 Kirch. Alg. Schl. p. 250. Cohn Nova Acta xxiv., t. 15, f. 

 15. 



var. 1. xninutissixna. RaJili. Alg. Eur. ir., 91. 



Trichomes abbreviated, more loosely spiral. 

 Spirillum minutissimum, Hass. Alg. 278, t. 75, f. 8. 

 Spirulina brevis, Kutz. Tab. Phyc. i., t. 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. c. 



In brackish ditches. 



Floating in large 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 XCri. 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. Micr. 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. 



