OEDOGONIUM 159 
195d. Var. majusculum Nordstedt. 
(PI. LX, fig. 591.) 
1878a, p. 21, Pl. 2, figs. 17-18; Hirn 1900, p. 246, Pl. XLI, fig. 257. 
Smaller; vegetative cell 14-2150-165y; suffultory cell 18-28x 
42-65u; oogonium 44-56 X 54-70u. 
Australia. 
Oe. acrosporum is readily identified by its single terminal 
oogonium and by the dovetailing of the longitudinal ridges of 
the inner surface of the oogonium and outer surface of the 
oospore. The varieties and form (see note under each) are 
separable largely on the basis of number of ribs and size of 
cells. The species is easily distinguished from Oe. tentoriale 
(No. 193) by its smaller number of longitudinal ribs on the 
oospore, by its more slender cells, and differently shaped 
oogonia. 
SPECIES IMPERFECTLY KNOWN. 
The following members of the genus are recorded with 
varying degrees of certainty regarding their validity. A few 
are unquestionably readily recognized even though a complete 
description is not available or possible at the present status 
of our knowledge. Some are very near other species, differing 
in one or more characters, but lacking sufficient completeness 
of description to warrant definite placement in the genus. 
Others are included purely as a matter of record. Wherever 
possible, the species is included in the key in its probably 
proper position, with the idea of calling it to the attention of 
the student of the genus and thereby aid in its identification if 
collected. Appropriate remarks occur in connection with the 
description of each species. 
196. Oe. tapeinosporum Wittrock. 
(Pl. XXXIV, fig. 314.) 
1874, p. 36; 1878, p. 140; De Toni 1889, p. 76; Oe. tapeinosporum var. Angolense 
West and West 1897, p. 5; Hirn 1900, p. 297, Pl. XXIII, fig. 117; Heering 1914, p. 224, 
fig. 344; Tiffany 1926, p. 96, Pl. VII, fig. 81. 
Oogonium 1-2, depressed-globose, operculate, division median, 
distinct; oospore depressed-globose, not (rarely nearly) filling oogonium, 
spore wall smooth; basal cell subhemispherical; termina! cell obtuse; 
vegetative cell (2-) 3-5X1040u; oogonium 15-19 (14-) 17-23; 
oospore 13-16 8—14y; basal cell 12-14 5-7y. 
United States: Iowa; England, Germany; Columbia; Africa; 
India. 
