OEDOGONIUM S87 
Distinguished from Oe. mexicanum (No. 44) by longer 
vegetative cells. Its obovoid and slightly larger oogonia 
usually separate it from Oe. grande, above. 
47. Oe. subrectum Hirn. 
(Pl. XX, figs. 181-183.) 
1900, p. 141,'Pl. XX, fig. 102. 
Dioecious, macrandrous; oogonium 1-2, subellipsoid or obovoid- 
ellipsoid, pore superior; oospore ellipsoid or globose-ellipsoid, filling or 
nearly filling oogonium, spore wall smooth, often thick; antheridium to 
9-seriate, sperms 2, division vertical; basal cell elongate; terminal 
cell apically obtuse; vegetative cell, female, 27-35 x 160-340yu, male 
26-33 X 104-800u; oogonium 70-83 X 83-1034; oospore 65-80 X 75—-93y; 
antheridium 22-28 x 8-14. 
Brazil. 
Characterized among the species with obovoid-ellipsoid 
oogonia by its size and the relatively long vegetative cells. 
48. Oe. landsboroughi (Hassall) Wittrock. 
(Pl. XXIV, figs. 211 and 212.) 
Vesiculifera landsborought Hass. 1842, p. 289, and 1845, p. 197, Pl. 51, fig. 2; 
Oe. landsborought Wittr. 1874, p. 35; Oe. gemelliparum Pringsh. in Rabenh. Alg. 
Eur. No. 1118, 1861; Oe. gemelliparum v. majus Wittr. 1870, p. 137; Oe. tumidulum 
Kuetz. in ibid No. 1468, 1863; Hirn 1900, p. 185, Pls. XVI and XVII, figs. 94 and 95; 
Collins 1909, p. 241; Heering 1914, p. 200, fig. 285; Tiffany 1926, p. 93, Pl. II, figs. 
12,and 13; P. B: A. No. 663: 
Dioecious, macrandrous; oogonium 1-2, (rarely 3), obovoid to ovoid, 
pore superior; oospore ovoid to ellipsoid, filling or not filling the oogoni- 
um, spore wall smooth; antheridium up to 30-seriate; sperms two, division 
vertical; basal cell elongate, terminal cell obtuse; female vegetative cell 
31-40 X90-240u, male 30-37 X120-225u; oogonium 63-78 X85-115y; 
oospore (55—) 59-70X73-102y; antheridium 27-35 X 9-20u. 
United States: Iowa, Ohio, Connecticut, Michigan, Massa- 
chusetts, New York, Mississippi; British Columbia; Paraguay, 
Uruguay; Mexico; Austria, England, Finland, France, Germany, 
Norway, Russia, Sweden. 
48a. Var. norvegicum Wittrock. 
(Pl. XXIV, figs. 213 and 214.) 
In Wittr. and Nordst. Alg. Exs. No. 204, 1879; Oe. landsboroughi var. robustum 
Wittr. in Wittr., Nordst. and Lagerh. Alg. Exs. No. 1215, 1896; Hirn 1900, p. 137, 
Pl. XVII, figs. 97 and 98; Tiffany 1926, p. 93. 
Vegetative cells shorter but of larger diameter; female vegetative 
cell 38-45 K 60-160u, male 36-45 X 55-135; oogonium 64-73 X 70-105; 
oospore 60-70 67-90y; antheridium 35-45 x 8—-l5uy. 
United States: Iowa; Norway; Brazil; Mexico. 
It is rather difficult to indicate the exact differences between 
the landsboroughi group and the crassum group in the genus, 
