ZYGNEMA 39 



Named in honor of Frank S. Collins, author of Freshwater Algae of 

 the United States and many contributions to both marine and fresh-water 

 algology. 



71. Zygnema melanosporum Lagerheim 1884. Bot. Zentralbl. 



18, p. 279. 



Vegetative cells 22-27 /a ^ 36-100 fi; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia cylindric or 

 slightly enlarged; zygospores ovoid to cylindric-ovoid, 23-30 /u, x 28-36 jia; 

 median spore wall dark blue, finely punctate. 



United States: Ohio, Fayetteville, May, 1934. 



Sweden; North Africa. 



72. Zygnema excompressum Transeau 1934. Trans. Amer. Micros. 



Soc. 53, p. 213. 



Vegetative cells 23-26 a^ x 32-80 ju; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia cylindric or 

 enlarged; zygospores globose to subglobose, more or less compressed in 

 the plane of the conjugating tube, 28yu, x 28-36 /x; median spore wall 

 blue, carinate, scrobiculate; pits 2.5-3 ju. ^^ diameter and about the same 

 distance apart. (PI. VI, Fig. 14.) 



United States: Oklahoma, Medford, April 26, 1932 (Taft Coll.). 



Bohemia. 



73. Zygnema peliosporum Wittrock 1868. Bot. Notiser. p. 190. 

 Vegetative cells 23-30 /a x 24-80 /x; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia enlarged, or in- 

 flated on the conjugating side; zygospores globose to ovoid, slightly 

 compressed, 28-36 m x 28-46 /a; median spore wall blue, finely scrobic- 

 ulate or punctate, with pits 1-2 /x in diameter, spaced 2-3 /a apart; equa- 

 torial suture usually distinct, sometimes prominent; aplanospores cylin- 

 dric-ovoid, smaller and with similar markings. (PI. VI, Fig. 17.) 



United States: California; Colorado; Texas; Indiana; Alabama. 

 Sweden; Hungary; Spain; France; Norway; Finland; China. 



74. Zygnema azureum Taft 1934. Trans. Amer. Micros. Soc. 



53, p. 214, PI. 17, Fig. 3. 



Vegetative cells 26-29 /* ^ 46-66 ju.; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia slightly to 

 greatly enlarged; zygospores ovoid to cylindric-ovoid, 27-33 /x ^ 33-50 /x; 

 median spore wall blue, finely punctate. (PI. VI, Fig. 15.) 



United States: Oklahoma; Illinois. 



75. Zygnema carinthiacum Beck 1929. Archiv f. Protist. 66, p. i. 

 Vegetative cells 25-30 )U x 25-1 00 fi; conjugation scalariform; zygo- 



