ZVGNKMACE^E. 95 



form a major. 

 Diameter of threads '05 mm. Bands 2 to 3. 



form (3 minor, 



Diameter of threads -032 mm. Band single. 

 SIZE. Zygospore -078--096 x -045 mm. 



Archer in Quart. Journ. Micr. Sci., 1873, xiii. p. 436. Petit 

 Spirogyra p. 11, t. 2, fig. 11-13. 



Spirogyra protecta, Wood. F. W. Alg. t. 14, f. 3. 



In bogs and moor pools. 



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

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



B. Chlorophyll bands single. 

 Spirogyra quadrat a. (Hass.) Petit. 



Sterile cells 3 to 9 times aslong as broad. Fertile cells turgid, 

 quadrate. Zygospore elliptical. Sporoderm brown. 



SIZE. Cells -024 to -027 mm. Zygospore 042--Q48 mm. 

 diam., 1* to 2 times as long. 



Petit Spirogyra p. 8, t. 1, fig. 13. Bull. Soc. Bot. France 

 xxi. p. 14, t. 1, fig. 2. 



Zygnema quadratum, Hass. Alg. 157, t. 37, f. 1, 2. Jenner 

 Fl. Tunb. Wells, 182. 



Rhynclionema quadrata, Kutz. Tab. Phy. v. t. 32, f. 6. 



In pools. 



We have accepted Petit's diagnosis of this species, which Hassall had 

 seen only with the Rhynchonema mode of conjugation, but which has 

 now been ascertained to conjugate in both ways. His description is very 

 short for a species which he says is "by no means uncommon," and he 

 evidently depends as a specific feature on the quadrangular enlarge- 

 ments of the fertile cells. " Cells usually seven or eight times as long as 

 broad. Sporangia oval, large, and much elongated, contained within 

 quadrangular enlargements of the cells." 



Plate XXXIX. Jig. 1. a, fertile cells in conjugation with zygospore 

 X - ; 00, after Petit ; fe, zygospore in cell X 400. 



Spirogyra Weberi. Kutz. 



Sterile cells with the extremities replicate, 7 to 12 times as 

 long as the diameter, chlorophyll bands single, 3 to 8 turns of 

 the spiral. 



Spores ovoid, scarce broader than the sterile threads, mem- 

 brane even, chestnut, twice as long as broad. 



Sporiferous cells scarcely turgid. 



SIZE. Spores : (a) -072 x -034 mm. (/3) -068 x '034 mm. 



Cleve Monog. Zygn. p. 25, t. vii., f. 1-10. 



form a. ineequalis. 



Diameter of thread '03 mm. Sporiferous cells scarcely 

 longer than the spores. 



Zygnema incequale, Hass. Alg. 150, t. 32, f. 1 to 2. 



Zygnema intermedium, Hass. Alt>\ t. 37, f. 3. Ann. Nat. 

 Hist. x. (1842) p. 41. Jenner Fl. Tunb. Wells, 182. 



