177 (Halsted. 
lorm «. Plants éarge, diffusely branched, sterile whorls con- 
sisting of few loosely branched leaves; fertile ones small and near the 
tips of the branches. 
Form . Plants small, delicate, slightly branched, somewhat . 
moniliform; whorls all fertile and dense. 
This species is subject to considerable variation, often approx- 
imating to the next, N. tenuissima, though usually distinguished from 
it by a looser habit and brighter green color. 
No. 27 of Braun, Raben. and Stiz. Exsic. is form s, which they 
eall ‘‘ Characteristische normalform.” No. 59, “forma simplicior,”’ is 
the normal form with smaller whorls. Some specimens from Dr. 
Robbins were like 59, while other plants from Uxbridge, Mass., were 
of an attenuated type and the finest specimens we have seen. 
The ten specimens in Nordstedt and Wahlstedt’s collection ex- 
hibit all gradations between the two forms figured in the plates. 
They make no varieties; but give five forms, their “forma laxior” 
being our form «. 
Kiitzing’s figure is of « and he gives no varieties in his Species 
Algarum. Reichenbach, Coss. and Germ., and the plate in the 
English Botany all agree with Kiitzing. 
In Herb. Gray are plants from New Mexico (C. Wright, No. 24.) 
It has also been collected at Brattleboro, Vt., (Frost); Essex Co. 
(Robinson); Uxbridge, Mass., and Harwich, Mass., (Dr. Robbins). 
. The diffusely branched form grows at Nobska Pond near Wood’s 
Holl, Mass. (Dr. Farlow), and Uxbridge, Mass. (Dr. Robbins). 
Nitella tenuissima (Desv.) Kiitz. 
Nitella tenuissima Kiitz. Phycol. germ., 256; Coss. and Germ., 
Fl. Env. Par., 683; Kiitz. Sp. Alg., 515; A. Braun, Schweiz. Char., 
10; in Krypt. Fl. Schlesien, 399. Chara tenuissima Desv., Bab- 
ington, Man. Bot., 433. 
Exsiccatae: Braun, Raber. and Stiz., Char. Exsic., 60. 
Illustrations: Reichenb., Iconog. Tab. 791-792, Figs. 4065-67 ; Coss. 
and Germ., Atlas, Tab. 41, F. 1 and 2; Kiitz., Tabulae Phycol., vir, 
Tab. 34, 8, 2. 
Plants monecious, small, slightly branched, moniliform, pale green; 
whorls compact, consisting of 6-8 leaves forming a globose cluster 
2.5-3.5 mm. broad; leaves repeatedly divided, the lower divisions 
5-7, upper usually three, last segment longest, ending with a small 
conical cell. Sporangia smail subelobose 1.5-2.5 mm. long; 6-8- 
striate, crown short. 
PROCEEDINGS B. 8, N, H.— VOL. XX 12 SEPTEMBER, 1879. 
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