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SPIROGYRA 213
forma gracilior). Czurda. Susswasserflora Mitteleuropa.
9, p. 147
(as S. calospora Cleve).
Vegetative cells 28-34 /a ^ 1 fi, 20-425 with replicate end walls; i,
rarely 2, chromatophores, making 2 to 6 turns; reproduction by zygo-
spores and aplanospores; conjugation scalariform ; tubes formed by
both gametangia; receptive gametangia cylindric or enlarged; zygo-
spores ovoid, 30-38 /x X 66-90 iit; outer spore wall of 2 layers, of which
the inner is thick, scrobiculate; median spore wall yellow, smooth;
aplanospores similar but smaller. (PI. XXXVII, Fig. 19.)
United States: Common throughout the eastern half.
Europe, recorded from France to Finland and the Ukraine.
Bessey in 1884 reported conjugation between S. protecta and S. majuscula
in both directions. Spore forms corresponded to those of the female
filament. Under the name S. calospora Cleve described 2 different forms;
the first, and larger, had i to 3 chromatophores and a yellow, scrobiculate
median spore wall. Wood published an accurate description in 1872.
238. Spirogyra cleveana Transeau 1934. Trans. Amer. Micros.
Soc. 53, p. 226. Jao. Sinensia. 6, p. 614, PI. 11, Fig. 120,
Vegetative cells 34-40 /x x ^u., 140-465 with rephcate end walls; i,
rarely 2, chromatophores, making 3 to 6 turns in the cell; conjugation
scalariform; tubes formed by both gametangia; sterile cells often greatly
inflated; fertile cells cyhndric or enlarged; zygospores ovoid to cylin-
dric-ovoid, 34-50 m x 70-125/*; outer spore wall hyaline, of 2 layers,
of which the inner is thick and coarsely scrobiculate; median spore wall
smooth, yellow. (PL XXXVIII, Fig. i.)
United States: Common in the eastern half.
China, Szechwan; probably includes the larger forms of S. calospora
(Cleve) in Europe.
239. Spirogyra denticulata Transeau 1934. Trans. Amer. Micros.
Soc. 53, p. 226.
Vegetative cells 42-56^ x 160-400 /x, with replicate end walls; i,
rarely 2, chromatophores, making 3 to 6 turns; conjugation scalariform;
tubes formed by both gametangia; fertile cells cylindric or enlarged;
sterile cells sometimes inflated; zygospores ovoid, 45-60 ju. x 76-130 ^c;
outer hyaUne spore wall of 2 layers; the outer thin, smooth; the inner,
thick, scrobiculate; median spore wall yellow, smooth. (PI. XXXVII,
Fig- 15-)
United States: Mississippi; Illinois; Indiana; Ohio; Massachusetts.
240. Spirogyra areolata Lagerheim 1883. Ofvers. Kgl. Vet.-AI{ad.
Forhandl. Stockholm. 40 (2), p. 56, PI. i, Figs. 18-20.
Vegetative cells 30-36 /x x 120-600 /x, with replicate end walls; i or