NITELLA OPACA. 99 



as to the identity of either of the two last-named. The Lake 

 Idwal plant, when collected subsequently by J. E. Griffith and 

 examined in a fresh condition, was found to be an extremely 

 slender form of N. opaca. In former years sufficient care was 

 not taken by British collectors in the selection and prepara- 

 tion of herbarium specimens of Charophyta, and in consequence 

 much of the material in the public collections is unsatisfactory 

 and inadequate for determination. 



The name by which the present species is generally known 

 is N. capitata, but inasmuch as there appears to be no doubt 

 as to the identity of the plant intended by the earlier published 

 name, capillaris, though the author's description is imperfect, 

 the rules of nomenclature give no option but to adopt it. 

 Were it allowable, it would be more satisfactory in this, as in 

 several other cases, to be able to retain the later name, especi- 

 ally as, in the present instance, it was accompanied by a good 

 illustration. 



[N.syncarpa Chevall., a species nearly related to N. capillaris, 

 is widely distributed in Europe, but has not yet been found in 

 the British Isles. This species has also the gelatinous envelop- 

 ment of the sexual organs, but the oospore is only faintly 

 ribbed and in the female plant the branchlets are not forked 

 but have a single secondary ray. The membrane is not 

 decorated.] 



2. Nitella opaca Agardh. 

 (PLATE VII.) 



Charaflexilis SMITH Engl. Bot. 1070 (excl. synon.) (1802). 

 C. opaca BRUZELIUS. Obs. Char. p. 23 (1824). 



Nitella opaca AGARDH Syst. Alg. p. 124 (1824). 



WALLMAN Forsok syst. Charac. p. 36 (1853) : Transl. p. 31 (1856). 

 WAHLSTEDT Bidrag Skand. Charac. p. 6 (1862) ; Mon. Sver. & Norg. 



Charac. p. 15 (1875). 

 NORDSTEDT in Bot. Notiser, 1863, p. 34. 

 CREPIN in Bull. Soc. Bot. Belg. II. p. 129 (1863). 

 LEONHARDI in Verb. Nat. ver. Briinn. II, p. 165 (1864). 

 BRAUN in Monatsb. Akad. Berl. for 1867, p. 875 (1868) ; in Cobn, 



Krypt. Fl. Schles. I, p. 397 (1876). 



GROVES in Journ. Bot. XVIII, p. 166, t, 210, f. 19 (1880). 

 MiiLLER in Bull. Soc. Bot, Geneve. II, p. 50 (1881). 

 COSSON & GERMAIN Atl. Fl. Par. ed. 2, t. 45 f.B (1882). 

 BRAUN & NORDSTEDT Fragm. Mon. Charac. p. 32 (1882). 

 SYDOW Europ. Charac. p. 14 (1882). 

 MIGULA Die Characeen p. 121. f. 35, 36 (1890) ; Syn. Charac. Europ. 



p. 31, f. 23, 24 (1898). 



HOLTZ Characeen, in Krypt. Mark-Brandenb. p. 71 (with fig.) (1903). 

 HY in Bull. Soc. Bot. France, LX. Mem. 26, p. 9 (1913). 



