OEDOGONIUM QO] 
Oe. paludosum is to be compared with Oe. boscii (No. 55) 
from which it differs in being monoecious. The two varieties 
are distinguished chiefly by relative sizes and by differently 
shaped and incompletely filled oogonia. 
54. Oc. leiopleurum Nordstedt and Hirn. 
(Pl. XXVI, figs. 221 and 222.) 
Rat Hirn 1900, p. 126, Pl. XIV, fig. 79; Oe. kjellmaniw Wittr. in Nordst. 1888a, 
p. 196. 
Dioecious, macrandrous; oogonium 1-4, obovoid (or ellipsoid- 
obovoid) or subellipsoid, pore superior; oospore obovoid-ellipsoid or 
subellipsoid, usually filling oogonium, spore wall in three layers: outer 
and middle layers with 26-80 longitudinal ribs, entire, sometimes 
anastomosate, inner layer smooth; antheridium to 24-seriate, sperms 2, 
division horizontal; basal cell elongate; terminal cell apically obtuse; 
female vegetative cell 15-2545-170u, male 15-17 X45-85y; oogonium 
40-51 X 65-83; oospore 39-49 X50-68u; antheridium 15-17 X7-15u. 
Africa. 
To be compared with Oe. boscii below. Its large number of 
seriate antheridia and usually completely filled oogonia are 
characteristic. 
55. Oe. boscii (Le Clerc) Wittrock. 
(Pl. XXVI, figs. 225 and 226.) 
1874, p. 34; (2?) Prolifera Boscii Le Clerc 1817, p. 474, Pl. 23, fig. 5; Conferva 
vesicata Ag. in Desmaz. Exs. 1845; Hirn 1900, p. 122, Pl. XIII, fig. 73; Wittr., 
Nordst. and Lagerh. Alg. Ex. No. 1218. 
Dioecious, macrandrous; oogonium 1 (rarely 2), oblong-ellipsoid, 
pore superior; oospore ellipsoid, not nearly filling oogonium longi- 
tudinally, spore wall of three layers: outer and middle layers with 
27-35 continuous, rarely anastomosate, longitudinal ribs; antheridium 
1-8, scattered, often in upper part of filament; sperms 2, division 
vertical; vegetative cell, female 14-23 X 45-135, male 13-18 X 52-108; 
oogonium 39-51 75—-110u; oospore 36-43 X 56—70y; antheridium 13-14 
X 6-16y. 
United States: Connecticut, Massachusetts, Iowa, Cali- 
fornia, Illinois, Ohio, Mississippi; Austria, England, Finland, 
France, Germany, Switzerland, Norway, Latvia, Sweden; 
Brazil; Greenland; British Columbia. 
55a. Form dispar Hirn. 
(Pl. XXVI, fig. 230.) 
1900, p. 124, Pl. XIV, fig. 76; P. B. A. No. 1226. 
Oospore smaller, ellipsoid-globose or subglobose; vegetative cell 
14-21 X 60-170u; oogonium 38-45 X 70-92u; oospore 34-43 & 44-55n. 
United States: Massachusetts, Pennsylvania, California. 
