Cladophora pulverulenta (Mertens) H.K.Phinney

Determined by Harry K. Phinney
Phycotheca Boreali-Americana. Collins, Holden <S Setchell.
De Toni, Syll. Alg., Vol. I, p. 319, 1889.
Collins, Green Algae of N. A., p. 340, 1909.
Conferva expansa Mertens in Juergens, Alg. Aquat., Dec. 8.
a.	Floating in mats on the surface of pools, "Sunken Meadow”,
Eastham, Massachusetts, Sept. 13, 1909.
b.	Lying loose on the bottom, same locality, April 19, 1907.
F. S. COLLINS.
At the station where this material was collected (see note to
No. 1611) the salinity of the water is quite low; Spirogyra species
are abundant, and the Cladophora fronds are beset with luxuriant
tufts of the fresh water blue-green alga, Calothrix stagnalis Gomont,
with well developed spores.
This species has been distributed in this series in five sets of
specimens, under four numbers, which together give a good idea of
the life cycle of the plant. No. 977 is a young plant, attached,
probably originating from the zoospore ; No. 121 is a later, loosely
floating form; 1633a is a later state of the same, the older parts hav-
ing taken on thick walls for the winter resting state ; in 1633b the
filaments of the preceding year are beginning to sprout, and in
1280 the process is still farther advanced.
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