118 BRITISH CHAEOPHYTA. 



Nitella gracilis AGARDH Syst. Alg. p. 125 (1824). 



COSSON & GERMAIN Atl. Flor. Par. t. 41, f.E (1845) ; ed. 2, t, 47, f.F 



(1882). 

 KUTZING Phyc, Germ. p. 256 (1845) ; Sp. Alg. p. 515 (1849) ; Tab. 



Phyc. t. 34, f. 1 (1857). 

 BRAUN in N. Denks. Schweiz. Ges. Natnrw. X, p. 10 (1847) ; in 



Monatsb. Akad. Berl. for 1867, p. 885 (1868) ; in Colin, Krypt. Fl. 



Schles. I, p. 399 (1876). 



RABENHORST Deutsch. Krypt. Fl. II, p. 194 (1847). 

 WALLMAN Fdrsok syst. Charac. p. 19 (1853) ; Transl. p. 17 (1856). 

 WAHLSTEDT Bidrag Skand. Charac. p. 1 (1862) ; Mon. Sver. & Norg. 



Charac. p. 19 (1875). 

 NORDSTEDT in Bot, Notiser, 1863, p. 38 ; in Flora Danica, t, 2930, i 



(1877). 



CREPIN in Bull. Soc. Bot. Belg. II. p. 128 (1863). 

 LEONHARDI in Verh. Naturf. ver. Bnmii, p. 170 (1864). 

 GROVES in Journ. Bot. XYIII, p. 164, t. 210, f. 15 (1880). 

 MULLER iii Bull. Soc. Bot, Geneve II, p. 52 (1881). 

 BRAUN & NORDSTEDT Fragni. Mon. Charac. p. 58 (1882). 

 SYDOW Enrop. Charac. p. 25 (1882). 

 BOSWELL Engl. Bot. ed. 3, XII, p. 183, t, 1903 (1884). 

 MIGULA Die Characeen, p. 159, f. 45-47 (1890) ; Syn. Charac. Europ. 



p. 39, f. 33-35 (1898). 



GIESENHAGEN Unters. ii. d. Charac. I, p. 63, ff. 29-36, 56 (1902). 

 HOLTZ Characeen, in Krypt. Mark-Brandeiib. p. 75 (1903). 

 HY in Bull. Soc. Bot. France LX, Mem. 26, p. 14 (1913). 



EXSICCATA : Areschong, 50 ( fide Walilstedt) ; Billot, 2992 ; Braun 

 Rabenh. & Stiz., 24, 25, 57-59 ; Desmazieres, 322 ; Fries, VII. 100 (fide 

 Sydow) ; Groves, 56; Lloyd, 423; Mougeot & Nessl. 1197; Migula, 

 Sydow & Wahlstedt. 51 ; Nielsen, 9 ( fide Walilstedt) ; Nordstedt & 

 Wahlst., 15-17; Rabenhorst, 138,169,439; Reichenbach, I. 99; Schultz, 

 IV. 91 ; Westendorp & Wall., 1094. 



Monoecious. Stem very slender ; internodes as long 

 to twice as long as the branchlets. Whorls of 5-6 

 slender branclilets. Branclilets 2-3 times divided ; 

 primary rays about a half the total length ; secondary 

 rays 3-5; tertian/ rays usually 3-4, of which 1-2 are 

 again forked. Ultimate rays 2-3 celled, penultimate 

 cell somewhat tapering upwards, usually not more, and 

 often considerably less, than twice as thick at the apex 

 as the base of the long narrowly-conical acute ulti- 

 mate cell. Third cell when present much longer than 

 the penultimate cell. Furcations often all fertile, an 

 oogonium or antheridium or both being present. 

 Oogonia solitary, at first subglobose, becoming ovoid- 

 conical through the lengthening of the spiral cells at 

 the apex, c. 525 /x long, 350 /x broad; spiral cells 



