298 
EDGAR NELSON TRANSEAU 
diam. veg. cell, female plant 
diam. veg. cell, male plant. . 
diam. oogonia 
diam.. oospores 
diam. antheridial cells 
10-17 length 35-95 m; 
8-15 /i, length 30-70 )u; 
33-40 /X, length 33-50 m; 
32-38 M, length 28-35 m; 
10-14 )U, length 13-18 M. 
The forms nearest to this species are Oe. acmandrium Elfv. and Oe. 
psaegmatosporum Norsdt. From these it is distinguished by its larger 
dimensions and dioecious habit. Among the poriferous species it 
bears some resemblance to Oe. rufescens Wittr. This species has been 
collected in Anderson's pools, on the Big Four R. R. right of way, just 
east of Charleston, Illinois, and in the ponds southeast of Lerna. It 
fruits in May. Type in herb. E. N. T. Collection No. 1797. Plate 
XXIX, figures 9-12. 
Oedogonium praticolum nov. sp. 
Oedogonium dioicum, (?) nannandrium, idioandrosporum ; oogoniis 
singulis vel rarius 2-7-continuis, ellipsoideis vel globoso-ellipsoideis, 
saepe terminalis, rarius sparsis; membrana oogonii interdum subcrassa, 
operculo apertis, circumscissione suprema, operculo minimo, deciduo; 
oosporis eadem forma ac oogoniis, haec plane complentibus, membrana 
laevi; cellulis suffultoriis eadem forma ac cellulis ceteris; plantis 
masculis paululo gracilioribus quam femineis; androsporangiis 1-20- 
cellularibus ; cellulis vegetativis leviter capitellatis; cellula fili basali 
forma, ut vulgo, elongata; cellula terminali apice apiculata vel in 
setam longam, tenuem, hyalinam, producta; 
crassit. cell, veget. plant, fern 16-26 /x, altit. 75-100/*;. 
crassit. cell, veget. plant, masc 14-22 fji, altit. 60-100 )u; 
Dioecious, (?) nannandrous, idioandrosporous ; oogonia single or 
more rarely in groups of 2-7, ellipsoid to globose-ellipsoid, often 
terminal, sometimes scattered; oogonium wall sometimes rather thick, 
operculate, division at the upper extremity of the oogonium, lid very 
small, deciduous; oospores of the same form as the oogonia, which 
they completely fill, wall smooth; suffultory cells similar to the other 
vegetative cells; male filaments a little smaller than the female; 
androsporangia i-20-celled; vegetative cells slightly capitellate ; basal 
cell of filament usually elongate; terminal cell apiculate or extended 
into a long, hyaline, tenuous seta; 
diam. veg. cells, female plant 16-26 length 75-100 
diam. veg. cells, male plant 14-22 n, length 60-100 /x; 
crassit oogon 
crassit. oospor 
crassit. cell, androsp. 
48-60 fjL, altit. 62- 74 
46-58 /X, altit. 60- 72 n; 
20-24 M» altit. 18- 22 n. 
