250 NEMATOGEN.E. 



Mack. Hib. 239. Gray. Arr. i., 281. Eng. Fl. v., 374. Eng. 

 Bot. ii., 2525. 



In ditches, swamps, inundated places, now and then free 

 swimming ; throughout the year. 



Yery variable, passing into several moderately distinct varieties, of 

 which the bright green one called viridis is the most beautiful, and by 

 no means rare. 



The form which Carmichael called Oscittatoria contexta has thus been 

 described by him : " Stratum of indefinite extent three feet and up- 

 wards, exceedingly thin, and peeling off in large flakes in dry weather, 

 of a deep but shining black colour, scored or striated in all directions. 

 These strise are caused by thick fasciculi of filaments, shooting out 

 either parallel to or across each other, changing their course from time 

 to time and sending off lateral fasciculi. The filaments are rather thick 

 about a line in length, straight or variously curved, of a greyish green 

 colour, and they radiate with great rapidity. A portion of the stratum, 

 not more than a line in diameter, placed in a watch-glass filled with 

 water, overspread the whole area of the glass with filaments in the 

 course of a night." Hassall says of it, " the filaments are in calibre not 

 less than those of O. tenuis, from which species it is distinguished 

 chiefly by its colour." 



Plate XCVL fig. 8. Portions of trichomes X 400. Plate XCVTI, 

 Jig. 1. Portions of trichomes of the variety viridis X 400. 



Oscillaxia antliaiia. Jury ens Alg. Exs. No. 14. 



Expanded in a gelatinous, sometimes very broad submem- 

 branaceous stratum, dark steel-blue. Trichomes rigid, straight, 

 sometimes tranquil, sometimes oscillating, curved at the attenu- 

 ated apex (curvature of 3 to 4 joints) ; joints equal, or nearly 

 equal,in length and breadth (after division half as long), dissepi- 

 ments distinctly granular, extreme apex obtusely rounded. Cell- 

 contents pale steel-blue, or blue green, nearly homogenous. 



SIZE. Threads -0045-'0055 mm. diam. 



Kutz. Tab. Phyc. i., t. 40, f. 6. Rabh. Alg. Eur. ii., 100. 



Oscillaria parietina, Vauch. Conf., t. 15, f. 8. 



Around pumps, cisterns, &c. 

 Plate XGyll. fig. 2. Portions of trichomes x 400. 



Oscillaria muscorum. Carm. HSS. 



Stratum 3-4 inches, of a dark bluish-green colour, slightly 

 lubricous, shortly radiating, creeping over mosses. Trichomes 

 variously curved, pale blue green, joints about equal in length 

 to their diameter. 



SIZE. Trichomes *006-'007 mm. diam. 



Hook. En^. Fl. v., 365. Harv. Man. 164. Hass. Alg. 

 252, t. 72, f. 12. 



In rapid streams, on Hypnum ruscifolium, &c. 



" Stratum 3 or 4 inches in extent, closely interwoven with the branches 

 and leaves of mosses, of a bluish green colour, and slightly lubricous 



