90 ZYGOPHYCER. 
Spirogyra quinina, Kutz. Tab. v. t. 22, f. 2. 
Spirogyra porticalis, Petit Spirogyra, p. 21, t. 5, f. 8-12. 
Conferva spiralis, Dillw. Conf. t.3. Eng. Bot. Ed.i. t. 1656. 
Zygnema spiralis, Eng. Bot. Ed. ii. t. 2561. 
Conjugata quinina, Gray Arr. i. 297, 
var. B. decimina. 
Chlorophyll bands usually 2, sometimes 8. 
Size. Cells -034--04 mm., 2 to 4 times as long. 
Zygnema deciminum, Hass. Alg. t. 23, f.3,4. Harv. Man. 
p. 148. Johnst. Fl. Berw. ii. 255. Mack. Fl. Hib. 2,31. Fl. 
Devon ii. 50. Jenner Fl. Tunb. Wells 178. Grev. FI. Edin. 
320. Eng. FI. v. 362. 
Spirogyra decimina, Kutz. tab. v. t. 28, f. 3, 24,f.1. Petit 
Spirogyra p. 25, t. 8, f. 1-3. Rabh. Alg. ili. p. 242. 
Spirogyra flavicans, Kutz. tab. v. t. 23, f. 3. 
Spirogyra laza, Kutz. Tab. v. t. 23, f. 3. 
Spirogyra major, Kutz. Tab. v. t. 24, f. 2. 
Conferva jugalis, Dillw. Conf. t. 5. 
Conferva inflata, Eng. Bot. Hd. i. t. 2376. 
Zygnema inflatum, Eng. Bot. Ed. ii. t. 2510. Hook. FI. 
Scot. ii. 80. 
Conjugata inflata, Gray Arr. i. 297. (?) 
Conjugata decimina, Gray Arr. i. 299. 
var.c. Yivularis. Hass. 
Size. Cells ‘032-036 mm., 5 to 10 times as long. 
Zygnema rivulare, Hass. Alg. 144, t. 27, f.1,2. Annals 
Nat. Hist. x. 38. 
Spirogyra rivularis, Rabh. Alg. Eur, iii. 243. 
Undoubtedly if the sterile threads of this species are carefully ex- 
amined, they will furnish abundant evidence that the number of spiral 
bands is variable, for cells will constantly be found in the same filament 
in which either one or two bands occur. So that, with the great simi- 
larity in fruit, it would be folly to think of maintaining the two varieties 
decimina and quinina as distinct species, on account of the number of 
chlorophyll bands. The Z. vivulare of Hassall, which we have included 
as a third variety, is not uncommonly found inasterile condition, in so 
far as it can be determined in this stage, but hitherto we have not seen 
it infruit. It issaid to be found on the Continent in fructification, but 
we have no knowledge of the Continental form. The spirals in the 
sterile cells are usually three, and then very nearly identical with the 
condition of the variety decimina, in which the bands are the same in 
number, 
Plate XXXV. fig. 1, form quinina. a, sterile cells X 200; }, ¢, conju- 
gating cells with zygospores X 200 ; d, outline zygospores X 400. Fig. 2, 
form decimina. 4, sterile cells X 200; 8, conjugating cells with zygo- 
spores X 200; d, outline zygospore X 400. Fig. 3, form rivularis. a, 
sterile cells X 200. 
