NITELLA TENUISSIMA. 121 



Groves in Journ. Bot. XVIII, p. 163, t. 209, f. 14 (1880). 



MtJLLEB in Btdl. Soc. Bot. Geneve II, p. 53 (1881). 



Bbattn & NoBDSTEDT Fi'agm. Mon. Oharac. p. 62 (1882). 



Stdow Europ. Oharac. p. 28 (1882). 



BoswELL Engl. Bot. ed. 3, XII, p. 184, 1. 1904 (1884). 



MiGTJLA Die Oharaceen, p. 173, f. 48-49 (1890) ; Syn. Oharac. Em-op. 



p. 45, f. 36, 37 (1898). 

 HoLTZ Oharaceen, in Krypt. Mark-Brandenb. p. 76 (1903). 

 Peospeb Oarofit. Espafl. p. 72, f. 12, a— c (1910). 

 Ht in Bull. Soc. Bot. Prance, LX, Mem. 26, p. 16 (1913). 

 N. exigua Wallmajst Forsok syst. Oharac. p. 38 (1853) ; Transl. p. 33 



(1856) ? 



ExsiccATA :— Areschoug, 394 ; Billot, 1985 ; Braun Rab. & Stiz. 60, 

 103 ; Desmazieres II. 323 ; Groves, 23, 24, 55 ; Giinther, Grab. & Wim. 

 1829, Oent XV (fide Sydow) ; Jack, Lein. & Stiz., 811 ; Lloyd, 421, 422 ; 

 Migula, Syd. & Wahlst., 3, 4, 126, 127 ; Nordstedt & Wahlstedt, 41 ; 

 Reichenbach, 100 (in some sets). 



Monoecious. Stem very slender, c. 250 /a thick ; 

 inte7-nodes 2-5 times the length of the branchlets. 

 Wliorls usually of 6 short somewhat spreading 

 branchlets. Branchlets of the fertile whorls 3-4 

 times furcate; ^primary rays -g-f the entire length; 

 secondary rays 6-7 ; tertiary rays 4-6, of which 1-4 

 are usually simple ; quaternary rays 2-5 of which 1 is 

 occasionally again furcate with 3-4 quinary rays. 

 Ultimate rays long narrow straight, invariably 2-celled ; 

 lower cell of uniform thickness, usually truncate at the 

 apex and but little broader than the base of the ulti- 

 mate cell; ultimate cellloTag narrow acnramate. Oogonia 

 and antheridia produced at the second and third (not 

 at the first) furcations, often together. Oogonia solitary, 

 at first spheroid or broadly ellipsoid, ultimately some- 

 what narrowed at both ends, when ripe c. 400 jjl long 

 (inch coronula), 260 /a broad ; spiral cells showing about 

 9 convolutions ; coronula c. 30-40 /a high, persistent. 

 Oospore roimdish-ellipsoid, conspicuously flattened c. 

 200-250^01 long, 175-200 ju, broad, 100-130 )u, thick, 

 showing 7-8 fine but well-defined low ridges ; order 

 membrane thin, flexible, and translucent, golden-yellow- 

 red, wine-red, or light red-brown, strongly reticulate, 

 with beaded reticulation threads (PL V, figs. 3-5). 

 Antheridium minute, c. 175 /x, in diameter. 



