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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; zygospores
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 ju. 2.5-3 ^^ 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-