ZYGNEMACES. 97 
Zygnema varians, Hass. Ann. Nat. Hist. xi. (1843) p. 431. 
Conjugatu inflata, Vauch. Conf. p. 68, t. 5, f. 3. 
Zygnema inflatum, Hass. Alg. t. 32, f.6, 7. Jenner Fl. Tunb. 
Wells, 180. 
Zygnema Jenneri, Hass. Alg. t. 37,f.6. Jenner Fl. Tunb. 
Wells, 182. 
Zygnema dubium, Hass. Alg. t. 37, f. 7. 
Spirogyra gastroides, Kutz. Tab. v. t. 29, f. 4. 
Rhynchonema Jenneri, Kutz. Tab. v. t. 32, f. 1. 
Rhynchonema dubium, Kutz. Tab, v. t. 82, f. 2. 
Spirogyra inflata, Rabh. Alg. Eur. iii, 233. 
In pools. 
This species includes the most delicate of British species with repli- 
cate ends to the cells. In all the forms of both varieties there is an 
evident tendency in the fertile cells to become more or less inflated. The 
only difference which Hassall indicates between his Z. inflatwm and Z. 
tenuissimum ig one of size, which may be influenced by the circum- 
stances of growth. 
Plate XXXTX. fig. 3. a, sterile cells X 200; b, conjugating cells of va- 
riety a, with zygospores X 200; ce, conjugating cells of variety b, with 
zygospores x 200; d, outline of zygospores X 400. 
GENUS 46. SIROGONIUM. Kutz. (1843.) 
Cells with parietal longitudinal chlorophyll bands. Fructi- 
fying cells diverse, arising by unequal division of the thread- 
cells, bending knee-like towards each other and growing 
together, united at the point of adnation ; receiving-cells barrel- 
shaped; giving-cells short, cylindrical. Zygospore (elliptic) in 
the receiving cell-wall. 
The sterile cells, with parallel chlorophyll bands, resemble those of 
Spirogyra, but differ in the genuflexuous conjugation. 
Sirogonium sticticum. Kutz. 
Sterile cells 2 to 5 times as long as broad. 
Zygospore broadly elliptical, spore-coat double. 
Sporiferous cells swollen, abbreviated, 
Size. Cells :04 to'05 mm., 2 to 5 times as long. Zygospore 
042 x ‘075 mm. 
De Bary Conj. p. 78, t. 2, figs. 1-67 Rabh. Alg. Eur. iii., 256. 
Sirogonium breviarticulatum, Kutz. Tab. Phy. v. t. 4. 
Sirogonium Braunit, Kutz. Tab. Phy. v. t. 4. 
Conferva stictica, Eng. Bot. t, 24638. 
Zygnema curvatum, Ag. Eng. Fl. v. 362. Harv. Man. p. 
148. Eng. Bot. Ed. ii. t. 2512, f. a. Hassall Alg. 148, t. 26, 
f.1, 2. 
Choaspes serpentina, Gray Arr. 1, 299. 
In ponds and ditches and moor pools. 
