160 THE OEDOGONIACEAE 
This species is rather readily distinguished by its conspicuous 
operculum and small size. No antheridia have been observed 
thus far. The Iowa material combined the characters of the 
type and the variety Angolense, and the latter thus becomes 
untenable. The species is perhaps dioecious, macrandrous. 
197. Oe. angustissimum West and West. 
(Pl. XXV, fig. 220.) 
1897, p. 6; Hirn 1900, p. 314, Pl. L, fig. 321. 
(?) Monoecious; oogonium 2, transversely inflated; oospore trans- 
versely elliptical and inflating oogonium, wall smooth; filament irregu- 
larly flexed and very narrow; vegetative cell 1.8-2X 13--28u; oogonium 
9.5X 10.5-14.5y; oospore 9.5 X6.5y. 
Africa. 
As far as is known, this is the smallest species of Oedo- 
gonium. Cf. Oe. inconspicuum (No. 198) and Oe. tapeinosporum 
(No. 196). 
198. Oe. inconspicuum Hirn. 
(Pl. XXXIV, fig. 313.) 
1895, p. 23, Pl. 1, fig. 8; 1900, p. 296, Pl. XXIII, fig. 116; (?) Oe. minutissimum 
Grun. in Hansgirg 1905, p. 436. 
(? Dioecious, macrandrous) Oogonium 1 (rarely 2-3), depressed- 
or subpyriform-globose, operculate, division median, narrow; oospore 
depressed-globose, filling the inflated part of oogonium, spore wall 
smooth; vegetative cell-3—-5 x 20-34; oogonium 138-18 (13-) 17-23; 
oospore 12-17 X8-12p. 
Columbia; Finland, Austria, Sweden. 
In common with most of the smaller sized species of the 
genus, Oe. inconspicuum is found attached to other alge or to 
submerged macrophytes. Cf. Oe. angustissimum above and 
Oe. tapeinosporum (No. 196). 
199. Oe. tenuissimum Hansgirg. 
1888a, p. 398; 1888, p. 222; Hirn 1900, p. 315. 
(2) Monoecious; filament irregularly curved; oogonium 1, subpyri- 
form, pore median; oospore globose-ellipsoid, not filling oogonium; 
vegetative cell 2.3-6X9-25yu; oogonium 9-18 X 14-23; oospore 15y in 
diameter. 
Austria. 
Characterized by its median pore and elongated oogonium; 
cf. Oe. sexangulare (No. 135) and Oe. pusillum (No. 200). 
