ZYGNEMACE.E. 87 



Spirogyra nitida^ Kutz. Tab. Phy. v. t. 27, f. 1. Kirscli. 

 Alg. Schl. p. 123. Petit Spirogyra p. 28, t. 10, f. 6 to 10. 



Conferva nitidum, Dill. Conf. t. 4, f. C. Eng. Bot. ed. i. t. 

 2337. Jermer Fl. Tunb. Wells 178. Gray Arr. i. 298. 



Zygnema rostratum, Hass. Alg. t. 33, f. 1. 



In ponds, &c. 



Very little requires to be said of this species, which is the most 

 common one with thick filaments in Britain. It is most probable that 

 HassalFs Zyynema rostratum is the same, conjugating longitudinally, for 

 he says that the filaments are somewhat larger than those of his 

 Zygnema nitidum, but that he had only seen it once, The form of 

 zygospore figured by him is that of the present species, and not of 

 Spirogyra bellis, to which the Rhynchonema rostrata of Kutzing is re- 

 ferred by Cleve. 



Cleve proposed to substitute the name of Spirogyra princeps, Vauch., 

 for the universally known Spirogyra nitida, a change with which we by no 

 means sympathise, because, after all, it is only a matter of opinion, and 

 not of demonstration, whether this is really the Conjugata princeps of 

 Vaucher, and there should be a good and substantial reasons for super- 

 seding a specific name so long recognised as Spirogyra nitida. 



Plate XXXIII. Jig. I. a, b, sterile cells X 200 ; c, conjugating cells 

 with zygospores X 200 ; d, outline of zygospore X 400. 



Spirogyra oxthospira. Nag. in Kutz. Spec. p. 441. 



Sterile cells with the extremities truncate, and from 2-| to 4 

 to 10 times as long as broad ; chlorophyll bands 3 to 4 to 5 

 (rarely 7), sometimes erect, sometimes forming a very lax 

 spiral. 



Spores orbicular, flattened, membrane even. 



Sporiferous cells scarcely swollen, 2-| to 4 times as long as 

 the diameter. 



SIZE. Cells *05-*065 mm. diam. ; zygospore '07 mm. diam., 

 048 mm. thick. 



Spirogyra orthospira, Archer in Quart. Journ. Micr. Sci., 

 1870. Petit Spirogyra p. 30, t. 10, f. 4, 5. 



Spirogyra majuscula, Kutz. Tab. Phy. v. t. 26, f. 1. Rabh. 

 Alg. iii. 244. 



In pools. Fruiting in autumn. 



This is a recently discovered species in the British Islands, and has 

 hitherto only been recognised by Mr. Archer in Ireland. 



Plate XXXIII. Jig. 2. a, a, sterile cells X 200 ; b, conjugating 

 cells with zygospores X 200 ; c, front and side views of zygospore X 

 400. 



Spixogyxa oxbiculaxis. Hassa.ll Alg. t. 19. 



Sterile cells with the ends truncate, about equal in length to 

 breadth; chlorophyll bands 5 to 7, making -^ to 1 turn. 

 Zygospores orbicular, flattened, membrane punctate. 

 Sporiferous cells not inflated. 



