86 ZYGOPHYCEJ:. 



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. (Petit), '14 mm. diam. 

 (Cleve), '075--1 mm. diam. (Rabh.), 'OST-'ll mm. diam. 

 (Kirsch.). Zygospores -14 x 'I-'IZ 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, f. 2 ; Petit Spirogyra 

 p. 29, t/1 1, f. 3, 4 ; Rabh. Alg. Eur. iii. 245. 



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 '13 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 X 200; ?>, fertile cells with 

 zygospores X 200; c, outline of zygospore X 400. 



Spirogyra nitida. (Dillw.) Link Handbk. in., 262. 



Sterile cells with the ends truncate, and usually 2 to 4 times 

 as long as broad ; chlorophyll bands about 4, making 1 to 4 

 turns of the spiral. 



Spores elliptic ovoid (almost almond-shaped), 1-| times as 

 long as broad, membrane even. 



Sporiferous cells persistent. 



Germinating plant clavate, radical cell much attenuated. 



SIZE. Herile cells -072--07S mm. diam. (Petit), '08-09 

 mm. (Clerc), -06--075 mm. (Rabh.), '054--077 mm. (Kirsch}, 

 07--09 mm. (M.C.C.). Zygospore -1 x ' 07 2 mm. (Cleve), '11- 

 13 X -06--07 mm. (M.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. 



Zygneina nitidum, Lyngb. Tent. Hydr. t. 59, f. B. Hass. 

 Alg. t. 22. Harv. Man. p. 143. Eng. Fl. v. 362. Eng. Bot. 

 Ed. ii. t. 2509. Mack. Fl. Hib. 231. Hook. Fl. Scot. ii. 80. 

 Dickie Bot. Guide 296. 



