178 ENGLISH BOTANY. 



glomerules. Nucules covered with mucilage, placed in the angles 

 between the branchlets and the rays, with 6 or 7 striae, and with the 

 spiral ridges on the central cell very prominent and acute. Globules 

 covered with mucilage, solitary in the forks of the rays, mostly on 

 axillary branchlets and crowded into small compact glomerules or 

 heads, from the branchlets being extremely short. 



Yar. y. opaca. Kiitzing. 

 Plate 1900. 



Braun, Babenh. & Stiz. Char. Europ. Exsicc. Nos. 29, 51, 52, 53, 77, 105, 106. 



Norclst. & Wahlst. Char. Scand. Exsicc. Nos. 5a, 5b, 6a, 6b, 7. 



Nitella syncarpa, var. opaca, Kiitz. Phyc. Germ. p. 256. 



N. syncarpa, vars. opaca, glomerata, and pachygyra, A. Braun, Scbweiz. Cbar. p. 7. 



N. opaca, Agardh, Syst. Alg. p. 124. A. Braun, Consp. Cbar. Europ. p. 1 ; in Gohn, 



Krypt. FL Scbles. Vol. I. p. 397 ; and Fragm. Monog. Cbar. p. 32. Nordst. in 



Anderss. Bot. Notiser, 1863, p. 34. Wahlst. Bidr. Skand. Cbar. p. 6 ; and 



Monog. Sver. Norg. Cbar. p. 15. Wallm. in Kongl. Vet. Akad. Handl. Stockb. 



1854, p. 264. Coss. & Germ. Fl. Envir. Par. ed. ii. p. 895 ; and Atlas pi. 45, f. b. 



Crepin in Bull. Soc. Bot. Belg. Vol. II. p. 129. Leonhardi in Brunn, Verbandl. 



Vol. II. p. 165. H. & J. Groves in Journ. Bot. 1880, p. 166, t. 210, f. 19. 



Baling. Man. ed. 8, p. 469. Miiller in Bull. Soc. Bot. Geneve, 1881, p. 50. 



Sydow, Europ. Cbar. p. 14. 

 N. atrovirens, Wallm. in Kongl. Vet. Akad. Handl. Stockb. 1854, p. 263. 

 N. pedunculata, Agardh, Syst. Alg. Introd. p. xxvii. 

 Cbara opaca, Agardh in Bruzel. Obs. Cbar. pp. 16 and 23. 

 C. flexilis, Sm. Engl. Bot. No. 1070. 

 C. syncarpa, Thuill. Fl. Envir. Par. p. 473. Ganterer, Osterr. Cbar. p. 9. Baling, in 



Ann. Nat. Hist. 1850, Vol. V. p. 83. 

 C. syncarpa, vars. opaca and pseudoflexilis, A. Braun in Flora, 1835, i. p. 52. 

 C. syncarpa, var. Smitbii, Coss. Germ. & Wedd. Cat. rais. PL Vase. Envir. Par. p. 151. 



Coss. & Germ. FL Envir. Par. ed. i. p. 682 ; and Atlas, pi. 39, f. 7-12. 



Olive. Branchlets of the female plant simple, forked or trifid ; 

 the primary are mostly barren, those of the axillary branches collected 

 into rather large, lax glomerules. Nucules not coated with mucilage, 

 placed in the angles between the branchlets and the rays, with 5 or 6 

 strise, and with the spiral ridges on the central cell rather prominent 

 and blunt. Globules not covered with mucilage, in the forks of the 

 rays, mostly on axillary branches, concealed in rather large lax 

 glomerules, from the branchlets being only moderately short. 



In lakes, ponds, pools, and ditches. 



Var. a. — Not known to occur in Britain, but very likely to be 

 detected, as it occurs in the north of France. 



