OEDOGONIUM, 115 
horizontal; vegetative cell 20-27 26-674; oogonium 48-58 x48-60y; 
oospore 43-50 (-54) 43-50 (—54)u; antheridium 18-22 9-11. 
Austria, France, Ireland, Latvia. 
110a. Form pseudautumnale Hirn. 
(Pl. XXXVI, fig. 346.) 
1900, p. 169, Pl. X XVII, fig. 153. 
A little smaller; vegetative cell 20-25 30-65u; oogonium 44-49 
45-55u; oospore 43-47 X48-47u; antheridium 19-22 10-14u. 
United States: Mississippi; France, Germany. 
Oe. rupestre has larger vegetative cells than any of the 
other monoecius operculate species with obovoid-globose to 
subglobose oogonia. It is to be compared with Oe. crisbum 
(No. 109). F. pseudautumnale has smaller fruiting cells than” 
the type. 
111. Oe. ahlstrandii Wittrock. 
(Pl. XXXVIII, fig. 358.) 
In Wittr. and Nordst. Exs. No. 401, 1882; Hirn 1900, p. 183, Pl. XXIX, fig. 179; 
Collins 1909, p. 247. 
Monoecious; oogonium 1, ellipsoid, operculate, division superior; 
oospore ellipsoid, filling oogonium, wall smooth; antheridium 1-2, 
hypogynous; sperms 2, division horizontal; terminal cell apically 
obtuse; vegetative cell 10-18X30-180u; oogonium 35-42 57-69u;. 
oospore 34-41 X53-62u; antheridium 13-17 X9-12u. 
United States: New York; Sweden, England. 
The large oogonium of this species separates it from all 
other ellipsoid, operculate, monoecious forms, except the still 
larger Oe. pachydermum, below. 
112. Oe. pachydermum Wittrock and Lundell. 
(Pl. XXXIX, figs. 377 and 378.) 
In Wittr. 1870, p. 125; Hirn 1900, p. 188, Pl. XXX, fig. 187. 
Monoecious; oogonium 1 (rarely 2), ellipsoid, operculate, division 
superior, wall frequently thickened; oospore ellipsoid, not filling 
oogonium, spore wall smooth; antheridium 1-3, hypogynous or sub- 
epigynous, often terminal; sperms 2, division horizontal; basal cell 
elongate; terminal cell apiculate; vegetative cell 21-2734-120y; 
oogonium 50-70 75-100u; oospore 40-60 * 50-80u; antheridium 18-21 
X 10-12u. 
Finland, Sweden. 
Cf. Oe. ahlstrandiut (No. 111). 
