CEDOGONIUM. 73 



Diameter veg. cells, 14-19 yu ; 2-2-3'> times longer. 

 Diameter oogon., 38-45 ^ by 42-50 //. 

 Diameter oospor., 33-39 yw by 31-37 yw. 

 Diameter sperm, cells, 12-14 u by 8-12 yw. 



Sluggish waters, Pennsylvania, New Jersey, California. 

 Plate LXXIV, figs. 20, 21. 



V 



OEDOGONIUM POLYMORPHUM, Wittr. and Lund. 



Oogonia single, rarely twin, globose-egg-shaped, opens by 

 pore above the middle ; oospore globose not filling the 

 oogoniuni closely ; sperniogonia 1-10 celled, often terminal, 

 subepigynous or vague and rare ; spermatozoids binate ; 

 terminal cell, obtuse, or apiculate or setiform. 



Diameter veg. cells, 8-14 yw ; 4-10 times as long. 

 Diameter oogon., 30-33 yw by 30-35 yw. 

 Diameter oospor., 25-30 ^ by 25-30 yw. 

 Diameter sperm, cells, 8 yw by 6-7 /-i. 



Brown's Mills and other ponds, New Jersey. 

 Plate LXXIV, figs. 16-19. 



OEDOGONITJM AUTUMNALE, Wittr. 



Oogonia single, obversely egg-shaped-globose, or globose, 

 opening by an operculum, fissure narrow ; oospore subglo- 

 bose filling the oogoniuni ; sperm ogonia 1-2 celled, subepi- 

 gynous or hypogynous, or sparse ; spermatozoids binate ; 

 terminal cell apiculate or rostellate. 



Diameter veg. cells, 16-19 yw ; li-2i times longer. 

 Diameter oogon. , 39-43 yw by 45-51 yw. 

 Diameter oospor. , 37-40 yw by 39-43 yw. 

 Diameter sperm, cells, 15-18 yw by 9-10 yw. 



Ponds and streamlets, Pennsylvania. 



Plate LXXXI, figs. 1, 2, 3, parts of filaments in fruit. 

 Figs. 4, 5, first stages of development from zoospores. 



Species ivith elliptic or oval oogonia. 



OEDOGONIUM URBICUM, Wittr. 



Oogonia single, elliptic, opens by a pore in superior part ; 

 oospore globose, not filling the oogonium ; spermogonia most 

 frequently only two celled ; spermatozoids binate ; the sup- 

 porting cells of oogonia usually destitute of chlorophyl. 



