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36
ZYGNEMATACEAE
zygospores globose to ovoid, 25-35^ x 33-40 ju, somewhat compressed;
median spore wall yellow-brown, reticulate, with large irregular pits
7-12 )Li across.
United States: Arkansas, Boston Mountains.
59. Zygnema stellinum (Vaucher) Agardh 1824. Systema Algarum,
p. 77.
Vegetative cells 28-38 /i x 27-ioo/A; conjugation scalariform, rarely
lateral between occasional pairs of cells; zygospores in one of the gametangia;
receptive gametangia inflated especially on the conjugating
side; zygospores ovoid, 30-42 /j. x 35-48 (-57)/^; median spore wall yellow-brown,
thick, scrobiculate; pits 3-4 i^^ in diameter, 3-4 /a apart;
aplanospores common, usually cylindric, very rarely globose, the former
filling the sporogenous cells, the latter occupying the middle of the
cells; spore walls similar to those of the zygospores. (Pi. I, Fig. 8;
PI. V, Fig. 16; and PL VI, Fig. i.)
United States: Washington and California eastward, very common in
the central and eastern states.
Canada; Greenland; Europe; Asia; South America; North Africa.
60. Zygnema cruciatum (Vaucher) Agardh 1817. Synopsis Algarum,
p. 102.
Vegetative cells 30-36 /it x 30-60 /x; conjugation scalariform; zygo-
spores in one of the gametangia; receptive gametangia cylindric or
enlarged; zygospores globose to ovoid, 30-38 ju. x iu,; 32-40 median spore
wall brown, scrobiculate; pits 1.5-2/A in diameter, i"- 3-5 apart; aplanospores
short, cylindric-ovoid, 30-35 /a x 30-60 /x, filling the vegetative
cells, otherwise similar to the zygospores. (PI. I, Fig. 9.)
United States: Oklahoma; Iowa; Illinois; Massachusetts south to Mis-
sissippi and Florida.
Reported from all the continents.
61. Zygnema cylindrosporum Czurda 1932. Siisswasserfiora Mit-
teleuropa. 9, p. 122, Fig. 126.
Vegetative cells 31-36 m x 60-80 m; conjugation scalariform; zygo-
spores in one of the gametangia; receptive gametangia cylindric or
enlarged; zygospores short cylindric-ovoid to globose, 36-42 /x x 42-60 /a;
median spore wall yellow-brown, scrobiculate; pits about 1.5-2 /a in
diameter, 3-5/* apart; suture obliquely encircling the smaller circum-
ference of the spore. (PI. VI, Fig. 2.)
Macedonia; northern India; South Africa.
62. Zygnema bohemicum Czurda 1932. Susswasserfiora Mittcl-
europa. 9, p. 124, Fig. 128.