ZYGNEMACER, 87 
Spirogyra nitida, Kutz. Tab. Phy. v. t. 27, f. 1. Kirsch. 
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. Jenner Fl. Tunb. Wells 178. Gray Arr. i. 298. 
Zygnema rostratum, Hass. Alg. t. 33, f. 1. 
In ponds, &e. 
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 
Hassall’s Zygnema rostratunt 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 mot 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 XXXTIT. fig.1. a, 6, sterile cells K 200; ¢, conjugating cells 
with zygospores X 200; d, outline of zygospore X 400. 
Spirogyra orthospira. Nig. in Kutz. Spec. p. 441. 
Sterile cells with the extremities truncate, and from 24 to 4 
to 10 times as long as broad; chlorophyll bands 8 to 4 to 5 
(rarely 7), sometimes erect, sometimes forming a very lax 
spiral. 
Spores orbicular, flattened, membrane even. 
Sporiferous cells scarcely swollen, 24 to 4 times as long as 
the diameter. 
Size. Cells ‘05-065 mm. diam.; zygospore ‘07 mm. diam., 
048 mm. thick. 
Srirogyra orthospira, Archer in Quart. Journ. Mier. 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 XXXII. fig. 2. a, a, sterile cells x 200; 3, conjugating 
cells with zygospores X 200; c¢, front and side views of zygospore X 
400. 
Spirogyra orbicularis. Hassall Alg. t. 19. 
Sterile cells with the ends truncate, about equal in length to 
breadth; chlorophyll bands 5 to 7, making 4 to 1 turn. 
Zygospores orbicular, flattened, membrane punctate. 
Sporiferous cells not inflated. 
