74 FRESH-WATER ALG.E OF THE UNITED STATES. 



Diameter veg. cells, 15-16 /.i ; 2 26 times longer. 

 Diameter oospor. , 33-45 // by 33-45 }.i. 



Syn. Oe. tumidum, Pringsli. 

 Plate LXXXII, fig. 10. 



Marsh pools, eastern counties of Pennsylvania. 



Species ivitti elliptic or oval oospor es. 



OEDOGONIUM PALUDOSUM, (Hass.) Wittr. 



Oogonia single, elliptic, sometimes subofolique, opens by a 

 pore above the middle ; oospore elliptic, moderately filling 

 the oogonium ; spermogonia 1-8 celled, sparse, usually in 

 upper end of filament ; spermatozoids binate. 



Diameter veg. cells, 15-20 /* ; 3-7 times longer. 

 Diameter oogon., 39-48 ^ by 66-84 //. 

 Diameter oospor. , 36-45 /* by 54-63 yw. 

 Diameter sperm, cells, 14-16 /< by 6-13 yw. 



Syn. Vesiculifera paludosa, Hass. 



Marsh pools, Northampton County, Pennsylvania. , 

 Plate LXXY, fig. 1. 



OEDOGONIUM CRASSUM, (Hass.) Wittr. 



Oogonia single, rarely twin, obovate- ellipsoid, somewhat 

 tumid, opening by a pore above the middle ; oospore ellip- 

 soidal nearly filling the oogonium, spermogonia 2-4 celled, 

 hypogynous or subhypogynous or epigynous; spermato- 

 zoids binate. 



Diameter veg. cells, 33-35 // ; 2-5 times longer. 

 Diameter oogonium, 65-70 ^ by 100-125 yw. 

 Diameter oospore, 60-66 j.t by 80-110 //. 

 Diameter sperm, cells, 30-33 // by 12-15 f-L 



Having found this species with spermogonia cells, not 

 heretofore observed, the diagnosis is adapted to our form. 

 Iowa and Kansas. 



Plate LXXYI, figs. 2 and 3. Two filaments with sper- 

 mogonia cells. 



OEDOGONIUM GRACILLIMUM, Wittr. and Lund. 



Oogonia single or twin, oblong ; opening by an oper- 

 culum, fissure narrow ; oospores oblong- elliptic, not filling 

 the oogonium ; spermogonia uni-bicellular, subepigynous ; 

 spermatozoids binate. 



