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40
ZYGNEMATACEAE
spores in one of the gametangia; receptive gamctangia much enlarged;
zygospores globose to ovoid, 32-45/1 x 36-52/1; median spore wall blue,
scrobiculate; pits 3-4/1 in diameter, 3-5/1 apart, (PL VI, Fig. 16.)
United States: Oklahoma; Texas; Mississippi; Ohio; Florida.
Austria; China.
Forms with the same vegetative characters, but with smaller spores,
have been collected in Ohio and Oklahoma.
76. Zygnema pawneanum Taft 1934. Trans. Amer. Micros. Soc.
53, p. 214, PI. 18, Fig. 16.
Vegetative cells 26-28/1 x 33-88/t; conjugation scalariform; zygo-
spores in one of the gametangia; receptive gametangia greatly enlarged
on the inner side; zygospores globose, subglobose, or rarely ovoid,
36-46/1 X 36-48/1; median spore wall blue when mature, pitted; pits
7-11/1 in diameter, 2-3/1 apart. (PI. VII, Fig. i.)
United States: Oklahoma; Louisiana (Taft Coll.); Ohio; Florida (J. D.
Smith Coll.).
In the Ohio collection some of the spores were distinctly tricarinate.
The pits may be round or somewhat angular depending upon the height of
the ridges between the pits.
77. Zygnema ornatum (Li) Transcau 1934. Ohio Jour. Sci. 34,
p. 420. Li. Ohio Jour. Sci. 33, p, 153, PL i, Figs. 9-10. 1933.
Vegetative cells 27-32 /c x 34-96/1; conjugation scalariform; zygo-
spores in one of the gametangia; receptive gametangia enlarged on the
inner side, or cylindric; zygospores globose, subglobose to ovoid, 28-38/1
x 32-38/1; median spore wall blue, pitted; pits about 6/1 in diameter
and about 2/1 apart. (PL VII, Fig. 2.)
United States: Oklahoma; Louisiana; Mississippi; Alabama.
China, Nanking (L. C. Li Coll.).
78. Zygnema excommune Transeau 1934. Trans. Amer. Micros.
Soc. 53, p. 213. Czurda. Siisswasserfiora Mitteleuropa.
p. 119 (as Z. commune)
Vegetative cells 30-32/1 x 55-90/1; conjugation scalariform; zygo-
spores formed in one of the gametangia; receptive gametangia greatly
enlarged on the ccmjugating side; zygospores globose to ovoid, 40/1 x
50/1; median spore wall blue, thick, scrobiculate; pits about 2.5/1 in
diameter, about 4/1 apart, according to the figure. (PL VII, Fig. 3.)
Bohemia.
79. Zygnema catenatum Transeau 1934. Trans. Amer. Micros.
Soc. 53, p. 213.
Vegetative cells 50-36/1 x 35-80/1; conjugation scalariform; zygo-