100 THe O28 DOGON ACE AE 
74a. Var. minus Hirn. 
(Pl. XXXII, fig. 280.) 
1900, p. 190, Pl. XXX, fig. 189; Oe. insignis Hirn var. minus Hirn 1895, p. 15. 
Larger oospore, ellipsoid, filling oogonium; vegetative cell 13-20 
80-240u; oogonium 60-63 85-1004; oospore 56-59X68-80u; anth- 
eridium 16-19 X12-17p. 
United States: Massachusetts; Finland. 
Oe. nobile ts near the larger Oe. insigne (No. 75) and differs 
from Oe. tumidulum (No. 73) in being monoecious. The 
variety minus sometimes has smaller vegetative cells and always 
a larger oospore than the type. 
75. Oe. insigne Hirn. 
(Pl. XXXIII, fig. 285.) 
1895, p. 14, Pl. 1, fig. 2; 1900, p. 191, Pl. XXX and XXXI, fig. 190. 
Monoecious; oogonium 1, ellipsoid-obovoid, operculate, division 
superior; oospore ellipsoid, quite filling oogonium, spore wall of three 
layers: outer smooth, inner longitudinally ribbed, the ribs quite entire, 
anastomosate, 40-45 in number, inner smooth; antheridium 1-7, 
subepigynous, rarely scattered; sperms 2, division horizontal; vegetative 
cell (18—) 25-88 X 75-210u; oogonium 70-78 X 100—120u; oospore 65-75 
X88-104y; antheridium 23-27 X 15-23y. 
Finland. 
Cf. Oe. tumidulum (No. 73) and Oe. nobile (No. 74). 
76. Oe. excisum Wittrock and Lundell. 
(Pl. XXXIV, fig. 317.) 
In Wittr. 1872; p. 3, Pl. 1, figs. 1-4; Hirn 1900, p. 153, Pl. XXIV, fig. 126. 
Monoecious; oogonium 1, subconically oblong, medianly plicate 
with about 9 longitudinal undulations, operculate, division median and 
broad; oospore ellipsoid with a median constriction, not filling oogonium, 
spore wall smooth; antheridium 1-2, subepigynous or hypogynous, often 
terminal; sperm (?) 1; basal cell subhemispherical; terminal cell apically 
obtuse; vegetative cell 83-6 X 14-44y; oogonium 13-15 X 18-26; oospore 
9-12 15-18u; antheridium 3-4 6-7; basal cell 8-9 4—5y. 
Finland, Sweden, Latvia. 
Oe. excisum is one of the very few species of the genus 
having an oospore with a median constriction. It is near 
Oe. pusillum (No. 221), from which it differs in having undulate 
folds in the oogonium. 
77. Oe. inversum Wittrock. 
(Pl. XXXIII, figs. 295-297. ) 
1876, p. 47, Pl. 13, figs. 22-24; (?) Oe. monticchu Fiorini-Mazzanti 1860, p. 259, 
Pl. 1, figs. 3, 4, 4a, 4b; Hirn 1900, p. 179, Pl. XXVIII, fig. 171; Oe. tnversum Wittr. 
var. subclusum Wittr. in Wittr. and Nordst. Alg. Exs. No. 26, 1877; Oe. inversum 
Wittr. f. subclusum (Wittr.) Hirn 1900, p. 180, Pl. XXVIII, fig. 172; Heering 1914, 
p. 208, fig. 290; Tiffany 1926, p. 95, Pl. VI, figs. 59-62. 
