438 Wisconsin Academy of Sciences , Arts, and Letters. 
tarum 30-40 p inter se distantibus; crassitudo cellularum 
6-7 M .” 
The typical form was not isolated but one with smaller 
cells was. 
GEOGRAPHICAL DISTRIBUTION 
EUROPE. Austria-Hungary (Brunnthaler, 1907; Hansgirg, 
1905; Reinhardt, 1905). Belgium (Conrad et Kufferath, 1912). 
Denmark (Chodat, 1900). Germany (Kolkowitz und Marsson, 
1908; Lemmermann, 1905B, 1907B, 1908D; Marsson, 1901B, 1904, 
1908A, 1908B, 1909, 1911; Schorler, 1907; Selk, 1907; Yolk, 1905). 
Sweden (Lemmermann, 1904A; Petersen, 1911). Switzerland 
(Bachmann, 1908; Chodat, 1894, 1901, 1902; Tanner-Fullmann, 
1906, 1907; de Wildemann, 1897A). 
ASIA AND OCEANIA. Australia (Playfair, 1912). India 
(Turner, 1892). Java (Bernard, 1908). Singapore (Lemmermann, 
1904C). 
Var. minor nov. var. (PI. XXIX: Figs. 70-74). 
Cellulis brevioribus; apicibus cellularum 18, 20, 24, 25, 
28 p inter se distantibus. Lat. cell. 3.4, 4.5, 6 p. 
The arrangement of the cells of the colony in the variety 
minor is similar to that of the typical form described by 
Lagerheim. The cells are never in a plane but always form 
a curved surface which at times is semicircular. The alga 
was isolated from material which had originally been col¬ 
lected from the shore of a bay in Lake Monona (Wisconsin) 
but which had been standing in the laboratory for some time. 
The station was revisited several times but the alga was not 
found in nature. Several strains were isolated from this col¬ 
lection all showing the same general characteristics. The 
number of cells in the colony is always four, as described by 
Lagerheim for S. acuminatus, but the cells are more irregular 
in shape, being typically lunate (Figs. 70, 71) but occa¬ 
sionally sigmoid (Fig. 72). In this feature they show a strik¬ 
ing similarity to the cells of Ankistrodesmus. The cells of 
the young colonies are very narrow but upon maturing in¬ 
crease in thickness without a corresponding increase in 
length. (Figs. 70 and 74.) 
