96 THE OED OGONT AG Eve 
oogonium, median layer of spore wall scrobiculate; suffultory cell 
enlarged; antheridium 1-7, division horizontal, sperms 2; basal cell 
ellipsoid-elongate; vegetative cell 21-22100—-240u; suffultory cell 
25-32 X 100-2304; oogonium 64-76X65-69u; oospore 54-65 55-66yu; 
antheridium 19-21 X 14—20u. 
United States: Michigan (Muskegon Lake). 
Oe. tiffanii is to be compared with Oe. scrobiculatum (No. 62) 
and Oe. verrucosum above. These three normally have smaller 
suffultory cells and are thus separated from Nos. 65-69. 
65. Oe. punctatum Wittrock. 
(Pl. XXIX, figs. 255 and 256.) 
1878, p. 142; De Toni 1889, p. 84; Hirn 1900, p. 132, Pl. XV, fig. 89. 
Dioecious, macrandrous; oogonium 1-4, obovoid (rarely globose- 
obovoid), pore superior; oospore obovoid, nearly filling oogonium 
(rarely subglobose and not filling oogonium), outer spore wall scrobicu- 
late; antheridium 1—5, often alternating with vegetative cell; sperms 2, 
division horizontal; basal cell elongate terminal cell (often .ocogonium) 
apically obtuse; vegetative cell 15-2242-128u; oogonitum 38-45 x 
52-65u; oospore 37-43 X 43-55y; antheridium 15-17 X6-10u. 
Mexico. 
Oe. punctatum, Oe. argenteum (No. 66), Oe. wyliez (No. 67), 
and Oe. americanum (No. 68) should be compared in identify- 
ing forms with scrobiculate oospores and non-tumid suffultory 
cells. They are easily separable on the basis of size. 
66. Oc. argenteum Hirn. 
(Pl. XXIX, figs. 253 and 254.) 
Hirn 1900, p. 289, Pl. VII, fig. 47; Ackley 1929, p. 302. 
Dioecious, macrandrous; oogonium 1, obovoid-globose to globose, 
pore superior (rarely supramedian); oospore ovoid to globose, outer - 
layer of spore wall scrobiculate; antheridia 3-4, sperms 2, division 
horizontal; basal cell elongate; female vegetative cell (14—) 20-28 
80-160u, male 20-2270-160u; oogonium 44-52X48-62u; oospore 
43-48 x 44—50u; antheridium 22 8u. 
United States: Michigan; Brazil. 
The figure of Oe. argenteum in Pl. XXIX 1s that of Hirn and 
represents also one of the variations occurring in the Michigan 
material. The outer oospore wall of the alga seen by Hirn 
(1900) is undoubtedly scrobiculate. _Ornamentations on ocspore 
walls are quite regularly constant for a given species, appearing 
definitely on one layer or another. The Michigan specimens 
(Ackley 1929) contained oospores whose middle wall layer was 
scrobiculate with an apparently smooth and very thin outer 
layer. It is perhaps best to include, for the present at least, 
