86 ZYGOPHYCEE. 
Spirogyra jugalis. (Dill.) 
Sterile cells with the ends truncate, and commonly equal, or 
double the length of the diameter. Chlorophyll bands 4 to 5, 
making 1 to 2 turns. 
Zygospore elliptical, membrane even. 
Sporiferous cells not swollen. 
Size. Sterile cells 09-1 mm. diam. (Petzt),-14 mm. diam. 
(Cleve), -075--1 mm. diam. (Rabdh.), -087--11 mm. diam. 
(Kirsch.). Zygospores -14 x *1-"12 mm. (Cleve), -15 x °1 
mm. (Petit), :13-"14 x :085--09 mm. (M.C.C.). 
Conferva jugalis, Dillw. Brit Conf. t. 5. ; 
Spirogyra jugalis, Kutz. Tab. v. t. 27, £.2; Petit Spirogyra 
p. 29, t.11, f. 3,4; Rabh. Alg. Eur. iii. 2435. 
Spirogyra setiformis, Petit Spirogyra, p. 29, t. 11, f. 1, 2 
(not Kutz., nor Rabh. Alg. Eur.); Rabh. Exs. 2292; Cleve 
Mon. Zyg. p. 15 (partly), t.1, f. 1-3. 
In clear ponds, &c. Fruiting at Midsummer. 
The British specimens which we refer to this species have the sterile 
cells from *12 to ‘14 mm. broad, and about two diameters long. The 
zygospore is from 18 to’14 mm. long and ‘085 mm, broad. In other 
specimens, from the Continent, we have found the zygospores from ‘11 
to °13 mm. long and (095 mm. broad. M. Petit recognises two species, 
which he calls respectively S. jugalis and S. setiformis, differing so little 
from each other that it seems scarcely possible to distinguish them except 
in extreme cases. To the latter he refers Z. interruptum of Hassall, 
but, without the fruit, which Hassall never found, it is difficult to affirm 
what it might be. It is quite as probable that it was S. orbicularis as 
anything else. 
Plate XXXII. fig. 2. a, sterile cells % 200; 5, fertile cells with 
zygospores X 200; ¢, outline of zygospore x 400. 
Spirogyra nitida. (Dillw.) Link Handbk. 111., 262. 
Sterile cells with the ends truncate, and usually 2 to 4 times 
as Jong as broad ; chlorophyll bands about 4, making 1 to 4 
turns of the spiral. 
Spores elliptic ovoid (almost almond-shaped), 14 times as 
long as broad, membrane even. 
Sporiferous cells persistent. 
Germinating plant clavate, radical cell: much attenuated. 
Size. Sterile cells -072--078 mm. diam. (Petit), -08--09 
mm, (Cleve), -06--075 mm. (Rabh.), 054-077 mm. (Kirsch ), 
*07--09 mm. (Jf.C.C.). Zygospore *1 x *072 mm. (Cleve), 11- 
‘18 X 06-07 mm. (1.C.C.). 
Spirogyra princeps, Cleve Monog. Zygn. p. 16, t. 1, f. 4 to 7. 
Conjugata princeps, Vauch. Conf. p. 64, t. 4, f. 1. 
Zygnema nitidum, Lyngb. Tent. Hydr. t. 49, f. B. Hass. 
Alg. t. 22. Harv. Man. p. 148. Eng. Fl. v. 362. Eng. Bot. 
Ed. ii. t. 2509. Mack. Fl. Hib. 231. Hook. FI. Scot. ii. 80. 
Dickie Bot. Guide 296. 
