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



filling the oogonium ; androsporangia 2-6 celled, dwarf 

 males obverse egg-shaped, situated on the oogonium. 



Diameter veg. cells, 10-12 yw ; 3-5 times longer. 

 Diameter oogon., 32-38 /u by 30-40 yw. 

 Diameter oospor., 29-34 yu by 25-28 yw. 

 Diameter androsp. cell, 9-10 yw by 11-15 p. 

 Diameter dwarf male, 6-7 yu by 14-15 yw. 



Syn. Oedog. vesicatum, D. By. 



Ponds, New Jersey, rare. 

 Plate LXXYTI, figs. 5, 6. 



OEDOGONIUM ARESCHOUGII, Wittr. 



Gynandrosporous, oogonia 2-6 continuous, or single, 

 rather depressedly globose, broadly cut round (circum- 

 scissile) in the middle, opening by a pore in the fissure ; 

 oospore exact globose, not filling the oogonium. Andro- 

 sporangia 1-6 celled, hypogynous or subepigynous, or 

 rarely scattered, terminal cell (which sometimes is the an 

 drosporangium) obtuse, dwarf males obversely egg-shaped, 

 seated on the oogonia. 



Diameter veg. cells, 9-12 yu ; 4-6 times longer. 



Diameter oogon., 38-39 yu by 36-40 //. 



Diameter oospor., 22-24 yw by 22-24 yw. 



Diameter androsp. cells, 10-11 yw by 10-12 /x 



Diameter dwarf males, 6-7 yu by 14-15 yw. 



Ponds, New Jersey. Oe. Areschougii is recorded with 

 some hesitation ; it is very near Oe. decipienx, the one may 

 be a mere variety of the other. 



Plate LXXVII, fig. 7, a filament with oogonia, dwarf 

 males, etc. 



OEDOGONIUM UNDULATUM, (Breb.) A. Br. 



Oogonia single or twin, elliptic-globose or subglobose, 

 opens by a pore below the middle ; oospore in form like the 

 oogonium, nearly filling it ; vegetative cells four times undu- 

 latingly constricted ; terminal cell (which is sometimes the 

 oogonium) obtuse; dwarf males elongate-obconical, seated 

 on the supporting cell. 



Diameter veg. cells, 15-17 yu 3-5 times longer. 

 Diameter oogon., 51-56 /< by 57-75 //. 

 Diameter oospor., 46-50 yu by 48-60 //. 

 Diameter dwarf males, 9-10 yw by 65-70 yw. 



