PLANKTON ALGA OF LAKE ERIE. 389 
Chlamydomonas globosa Snow, new species (fig. II). 
Cells spherical or slightly ellipsoidal, 5.2 to 7.8 /< in diameter; membrane smooth at anterior 
end; two flagella as long or slightly longer than the cell; pigment spot small and inconspicuous; 
chloroplast much thickened at the posterior end; pyrenoid present; a pulsating vacuole at anterior 
end. Gametes not found. Locality, plankton of Lake Erie. 
Fusola viridis Snow, new genus and new species (fig. V1). 
Cells fusiform or slightly sigmoid, 27 to 29 “< long and 6.5 to 21 4 broad, each cell surrounded 
by a thick, homogeneous, gelatinous envelope, the outer line of demarcation being prominent; 
color a bright green. The chloroplast occupies most of the cell except for a small spherical cavity 
near the center, in which lies the nucleus; a pyrenoid is present. Reproduction by means of divi- 
sion of the contents into two, the halves gradually assuming the shape of the mother cell, during 
which process the enveloping membrane becomes obliquely ruptured. Membrane of cellulose. 
Large masses of cells may be formed in the presence of a great amount of nutritive substance. 
Loeality, a pond on Middle Bass Island, Lake Erie. 
Chodatella citriformis Snow, new species (fig. VIII). 
Cells ellipsoidal with an obtuse projection at either end; length 13 to 23 4, breadth 8 to 20 wu; 
spines slender, forming whorls at the bases of the projections. Chloroplast single, parietal, lying 
lengthwise of the cell. Reproduction by division of the contents of the parent cell into 4 or 8, 
each part becoming invested with a membrane and thus fcrming a complete individual, Found 
in surface and deep tow of Lake Erie. 
Pleurococcus aquaticus Snow, new species (fig. X). 
_ Cells 4 to 7 « in diameter, existing either as spherical or ellipsoidal individual cells, or as some- 
what angled cells combined into large cubical or irregular masses. Membrane thin, chloroplast 
concave, with an opening at one side; no pyrenoid. Reproduction by division of membrane and 
contents alternating in three directions of space. Locality, the plankton of Lake Erie. 
Chlorococcum natans Snow, new species (fig. XI). 
Cells spherical or slightly elongated, not exceeding 13 « in diameter. Membrane of cellulose; 
chloroplast concave, of the shape of the cell, with a circular opening at one side; nucleus single in 
young individuals, but just before reproduction of the same number as the zoospores. In 2 per 
cent Knop’s solution the organism often forms gonidia, while in weak organic solution it passes 
into a palmella condition in which the cells are oblong. Zoospores 6.5 to 8 u long, 2.5 to 3.25 
broad. with two flagella, a concave chloroplast, a pyrenoid, a pigment spot, and two pulsating 
vacuoles. Locality, plankton of Lake Erie. 
Botrydiopsis eriensis Snow, new species (fig. XII). 
Cells spherical, 18 to 21 2 in diameter; the chloroplasts in mature cells elongated and irregu- 
larly arranged, in young cells appearing as hexagonal disks closely applied to the membrane. 
Zoospores 2.5 /4 long, 2.5 to 3.25 « broad, with two chloroplasts, a single flagellum, a pigment spot, 
and two contracting vacuoles. Usually 16 zoospores formed in a cell; when liberated the inner 
layer of the mother membrane emerges with the zoospores from the outer layer. MWocality, 
plankton of Lake Erie. 
Botrydiopsis oleacea Snow, new species (fig. XIII). 
Cells spherical, ellipsoidal or lemon-shaped, not exceeding 16 /¢ in diameter, containing numer- 
ous minute particles of oil which obscure the outline of the chloroplasts; near the center a large, 
prominent, dull-red globule; membrane of cellulose. Zoospores pear-shaped, 2, 4, 8, or 16 in 
number, formed from repeated bipartition of the cell contents, excepting the red globule; size of 
zoospores 5 to 7, 8 4 by 3 to 5 “; character amceboid; flagellum single at smaller end; pigment spot 
present; chloroplasts obscured by oil, two of them discernible in germinating cells. Zoospores 
liberated by the softening of the entire enveloping membrane. Under unfavorable conditions a 
resting stage is assumed, the membrane becomes thick, and the contents assume a yellow color. 
Locality, the plankton of Lake Erie. 
