OEDOGONIUM 141 
This species is characterized by its capitellate vegetative 
cells, wide operculum, small size, and small oospores in com- 
parison with oogonia. Var. americanum differs from the species 
in being idioandrosporous; f. rebustum in addition has larger 
oospores. 
161. Oe. confertum Hirn. 
(Pl. LIV, fig. 510.) 
1900, p. 272, Pl. XLVI, fig. 291. 
Dioecious, nannandrous, (?) idioandrosporous; oogonium 1-4, 
depressed-globose or depressed pyriform, operculate, division median, 
wide; oospore globose or subdepressed-globose, not filling oogonium 
longitudinally, spore wall smooth; vegetative cell capitellate; dwarf 
male obovoid, on oogonium; vegetative cell 19-26 x 66-105u; oogonium 
56-63 X 44-56u; oospore 42-48 X 40-44; dwarf male 10-12 13-16n. 
Australia. 
To be compared with Oe. areschougit (No. 160), which is 
smaller and has less depressed oogonia. It is also similar in 
appearance to the larger Oe. perspicuum, below. 
162. Oe. perspicuum Hirn. 
(Pl. LIV, fig. 511.) 
1900, p. 273, Pl. XLVI, fig. 293; Oe. diotcum Carter in West and West 1901, p. 
175, Pl. IV, fig. 42. 
Dioecious, nannandrous; oogonium 1-8, depressed or subdepressed- 
globose, operculate, division median, broad; oospore globose or sub- 
globose, not filling oogonium longitudinally, spore wall smooth; dwarf 
male obovoid, unicellular, on oogonium; vegetative cell (80—) 35-43 
95-175u; oogonium 89-100 64-104y; oospore 55-70 52-70u; dwarf 
male 15-18 X 19—22n. 
Australia; Siam. 
Cf. Oe. confertum, above. 
163. Oc. clavatum Hallas. 
(Pl. LIV, figs. 512 and 513.) 
1905, p. 399, fig. 3; Hirn 1906, p. 11, Pl. IV, fig. 28. 
Dioecious, nannandrous, gynandrosporous; oogonium 1-3, sub- 
pyriform to subdepressed-globose, operculate, division a little above 
medium; oospore subdepressed, depressed-globose, or globose, quite 
filling oogonium (rarely not), spore wall smooth; androsporangium 1-2, 
scattered; dwarf male obovoid, unicellular, on oogonium; vegetative 
cell capitellate or nearly clavate; basal cell subhemispherical; vegetative 
cell 2-9X5-80u; oogonium 14-26 16-2lu; oospore 12-21X12-14u; 
androsporangium 4—6X5-7y; dwarf male 6X 14—-15y. 
United States: New York (Long Island); Denmark. 
One of the smallest nannandrous species with capitellate 
or nearly clavate vegetative cells. 
