448 Wisconsin Academy of Sciences , Arts , and Letters. 
transversalis duae partes diametri longitudinalis; familae 
plerumque ex cellulis octonis constitutae, cellalue singulae 
laterale accumbentes, perfecte alternates.” 
“Cellulae. longit. 13-16 y; cellulae latit. 10-13 /x.” 
The typical fom of S. bijuga is known to have the cells 
arranged sub alternately at times but the isolating of a strain 
where the cells are constantly arranged in an alternate posi¬ 
tion warrants the retention of the variety alternans. It is 
very probable, however, that in many cases the typical S. 
bijuga has been called S. bijuga var. alternans. 
GEOGRAPHICAL DISTRIBUTION. 
EUROPE. Austria-Hungary. (Hansgirg, 1886, 1905; Pascher, 
1903; Reinhardt, 1905). England (G. S. West, 1899; W. West, 
1892B; West and West, 1897B). France (Reinsch, 1866, 1867). 
Germany (Lemmermann, 1893, 1899; Marsson, 1911; Schmidle, 
1894; Volk, 1903, 1905; Weiss, 1892). Ireland (Adams, 1908; 
W. West, 1892A; West and West, 1902B). Scotland (W. West, 
1903). Sweden (Borge, 1895, 1907A, 1913; Lagerheim, 1883B; 
Lemmermann, 1904A). Switzerland (Ghodat, 1902; Dalla Torre 
und von Sarnthein, 1901; Huber, 1905, 1908). 
AFRICA. Azores (Bohlin, 1902). Lake Nyassa (Schmidle, 
1903, 1904). Lake Rukuga (Schmidle, 1904). 
AMERICAS. Brazil (Bohlin, 1897). Paraguay (Bohlin, 1897). 
Puerto Rico (Collins, 1909; Lagerheim, 1887). United States 
(Collins, 1909; Snow, 1903). 
Var. alternans forma parvus nov. forma. (PI. XXX: 
Figs. 106-108.) 
Dimens. cell. 8-9 y x 3.5-4 y. 
The cells of this strain isolated never reach the minimal 
dimensions as given by Reinsch so it is regarded as a form 
of S. bijuga var. alternans. 
Var. irregularis (Wille) nov. comb. (PI. XXVIII: 
Figs. 59-62.) 
S. bijugatus forma irregularis. Wille, 1903, p. 92; Fig. 4. 
Cellulis irregulariter dispositis in seriem duplicem aut 
alternatim. Dimens. cell. 10 x 6, 10 x 5, 8 x 4, 7.5 x 3.5 /x- 
I have isolated this variety several times. The coenobia 
usually contain eight cells, arranged in an irregular double 
series, although four-celled coenobia where the cells are fre- 
