Zygnema cyanosporum Cleve 1869, p. 28 



Vegetative cells (17)-20-(27);u in diameter and up to 9 times the 

 diameter in length; fertile cells not inflated. Zygospores formed in 

 the tube; globose or depressed-globose, compressed at right angles 

 to the tube; median layer blue and smooth; 34-40;ii in diameter. 



Mich. 



Zygnema decussatum (Vauch.) Transeau 1914, p. 290 



Vegetative cells 18-20/^ in diameter and up to 100/x long, the wall 

 without a thick layer of mucilage; fertile cells not inflated. Zygo- 

 spores formed in the tube; globose or depressed-globose; median 

 spore wall brown and scrobiculate; 27-30/^ in diameter. 



Mich. 



Zygnema insigne ( Hass. ) Kuetzing 1849, p. 444 



Vegetative cells 26-30/a in diameter, 1-2 times the diameter in 

 length; fertile cells cylindrical or inflated on one side only. Zygo- 

 spores formed in one of the gametangia; subglobose to ovate; median 

 wall brown and smooth; 32/^, in diameter, or (ovate spores) 26/x in 

 diameter, 32^ long. 



Mich. 



Zygnema leiospermum DeBary 1858, p. 77 

 PI. 78, Fig. 13 



Vegetative cells 20-24/i, in diameter, quadrate; fertile cells enlarged 

 but not distinctly inflated. Zygospores foraied in one of the game- 

 tangia; globose; median wall brown and smooth; 23-30/x in diameter, 



Mich. 



Zygnema micropunctatum Transeau 1934, p. 210 

 PL 78, 'Fig. 12 



Vegetative cells 14-16/i, in diameter, 24-52/a long; fertile cells 

 not inflated. Zygospores formed in the tube; depressed-globose or 

 ovate, compressed at right angles to the conjugation tube; median 

 wall yellow-brown and minutely punctate; 28-32/x in diameter, 

 36-40/x long. 



Mich. 



Zygnema pectinatum (Vauch.) C. A. Agardh 1817, p. 102 



PI. 69, Figs. 9, 10 



Filaments forming light green, cottony masses; vegetative eells 

 30-37-(40)^ in diameter, up to 80|U, long, usually inclosed by a soft 

 mucilaginous sheath; fertile cells not inflated. Zygospores formed 



[325] 



