OEDOGONIUM Toe 
193. Oe. tentoriale Nordstedt and Hirn. 
(Pl. LXI, fig. 597.) 
In Hirn 1900, p. 248, Pl. XLII, fig. 260. 
Dioecious, nannandrous; oogonium 1, terminal, broadly ellipsoid 
or obovoid-globose, division supreme, lid small, deciduous, oogonium 
wall longitudinally ribbed on the inner surface, ribs often anastomosate; 
oospore quite filling oogonium, outer layer of the spore wall with 40-45 
longitudinal, very finely crenulate ribs, closely filling in between the 
ribs of the oogonium, connected by delicate transverse lines, inner 
layer smooth; basal cell elongate; terminal cell obtuse; dwarf male 
suberect, on suffultory cell, antheridium exterior 1—?; vegetative cell 
20-33 (-37) 60-225; oogonium 66-82X73-88y; dwarf male stipe 
10-15 X37-48u; antheridium 9-12 7u. 
United States: Illinois; Brazil. 
Cf. Oe. acrosporum (No. 195). 
194. Oe. michiganense Tiffany. 
(Pl. LXI, figs. 594-596.) 
1927505 20D el exe iss OSI. 
Dioecious, nannandrous, gynandrosporous; oogonium 1-7, globose 
to ellipsoid-globose (rarely subglobose), operculate, division at the 
upper extremity of the oogonium; oospore globose, filling the oogonium 
or not, outer layer of spore wall smooth, middle layer with 12-24 
crenulate, sometimes anastomosing, longitudinal ribs, inner layer 
smooth; suffultory cell enlarged; vegetative cell broadly capitellate; 
basal cell elongate; terminal cell, occasionally oogonium, apically 
obtuse; dwarf male, a little curved, on suffultory cell, antheridium 
interior; vegetative cell 12-24 80-160y; suffultory cell 32-48 x 64-80u; 
oogonium 50-64 50-80u; oospores 44-60 44-60u; androsporangium 
16-20 x 16—20u; dwarf male 14-20 X40—56y; basal cell 18-20 70-100u. 
United States: Michigan. 
The only nannandrous member of the genus possessing a 
capitellate vegetative cell, a supreme operculum, and longi- 
tudinally ribbed oospores. 
195. Oe. acrosporum De Bary. 
(Pl. LX, fig. 589.) 
1854, p. 47 et seq., Pl. 3, figs. 1-12; Oe. acrosporum De Bary f. connectens Wittr. 
in Wittr. and Nordst. Exs. No. 1101, 1893, ix P. B. A. No. 409, 1898, zx Hirn 1900, 
p. 245, Pl. XLI, fig. 255; Hirn 1900, p. 244, Pl. XLI, fig. 254; Collins 1909, p. 259; 
Heering 1914, p. 183, fig. 253; Tiffany 1926, p. 107, Pl. IX, fig. 103. 
Dioecious, nannandrous, gynandrosporous (or idioandrosporous) ; 
oogonium 1, terminal, ellipsoid, operculate, division supreme, operculum 
small and deciduous; wall of oogonium with longitudinal, sometimes 
anastomosing, ridges on the inner surface; oospore quite filling the 
oogonium, outer layer of spore wall with 23-30 longitudinal ridges, 
closely fitting in between the ridges of the oogonium, inner smooth; 
basal cell elongate; terminal cell obtuse; androsporangia 1-2, hypo- 
