Bower oce LE TE 3D 
United States: Michigan, Illinois; Australia, Finland, Ger- 
many, Norway, Sweden, Denmark, Patagonia. 
B. crenulata has often been confused with forms of B. 
intermedia, since the ‘‘crenulations’’ of the oospore walls are 
not always distinctly “‘crenulate.’’ It seems best, however, to 
retain the two as distinct species because (1) the latter normally 
has longer cells in proportion to diameter and (2) the two 
species normally represent extremes of a series of gradations 
in oospore wall ornamentation: B. intermedia may have nearly 
smooth to scrobiculate oospores, while those of B. crenulata 
vary from distinctly scrobiculate to crenulate. 
12. B. intermedia De Bary. 
(Pl. I, fig. 5.) 
1854, p. 72, Pl. 4, figs. 1-7; Wittrock 1874, p. 44; B. crenulata Pringsh. var. 
supremediana Wittr. 1883 in Wittr. and Nordst. Alg. Exs. Fasc. 11, No. 509; (?) 
B. elachistandria Wittr. in Borge 1896, p. 3; Hirn 1900, p. 326, Pl. LII, fig. 333; 
B. intermedia De Bary f. americana Hirn 1900, p. 328, Pl. LII, fig. 334; B. intermedia 
De Bary f. supramediana (Wittr.) Hirn 1900, p. 328, Pl. LII, fig. 335; Hirn 1906, 
p. 56; Collins 1909, p. 268, fig. 82; Heering 1914, p. 233, fig. 358; Tiffany 1926, p. 109, 
Berio O 7m O2Se pels ible oeiyn tesa PB. Av Non 973: 
Dioecious, nannandrous, gynandrosporous; oogonia subdepressed- 
globose, patent, below androsporangia; division of suffultory cells 
nearly median; outer wall of oospore scrobiculate, rarely apparently 
smooth; androsporangia 1-2, epigyncous or rarely scattered; dwarf 
males on the oogonium; antheridium interior, stipe slightly curved, 
shorter than the antheridium; vegetative cells 17-20 35-70u; oogonia 
40-48 X 31—40y; oospores 38-46 X 30-38; androsporangial cells 11-13 X 
7-12u; dwarf males 9-10 X 21—26u. 
United States: Iowa, Illinois, Ohio, Michigan, Connecticut, 
Pennsylvania, Massachusetts, Alaska; Canada, Australia, 
Europe, Greenland, Africa. 
12a. Var. depressa Wittrock. 
(Pl. I, fig. 6.) 
1874, p. 44, Pl. 1, fig. 18; Hirn 1900, p. 329, Pl. LII, fig. 336; B. intermedia 
De Bary var. depressa Hirn in Heering 1914, p. 233; Tiffany 1926, p. 109; 1928, 
p. 137, Pl. XIV, fig. 6. 
Vegetative cells a little longer than in the type; oogonia depressed- 
globose; outer oospore wall scrobiculate, often nearly smooth; division 
of suffultory cell a little above the median position (rarely a little below 
median); vegetative cells 14-19X35-88yu; oogonia 42-4630—40p; 
oospores 40-44 28-38u; androsporangial cells 11-13X9-12u; dwarf 
males 9-11 22-25 
United Stas: Iowa; Finland, Germany, Norway, Sweden; 
British Columbia. 
Hirn recognized with B. intermedia its variety depressa and 
two forms, americana Hirn and supramediana (Wittrock) 
