72 FRESH- WATER ALG^E OF THE UNITED STATES. 



OEDOGONIUM VERNALE, (Hass. ) Wittr. 



Oogonia single, obversely egg-shaped, opening with an 

 operculuni, fissures narrow ; oospore globose not filling the 

 oogonium ; spermogonia bicellular, subepigynous. 



Diameter veg. cells, 10-16 yu ; 4-6 times as long. 

 Diameter oogoii., 39-45 yw by 45-51 yw. 

 Diameter oospor., 34-38 yu by 34-39 yu. 

 Diameter sperm, cells, 10-12 yu by 8-9 yu. 



Syn. Vesiculifera vernalis, Hass. ; Vesiculifera Candollei, Hass. 



Ponds, Pennsylvania. 

 Plate LXXIV, figs. 9, 10. 



OEDOGONIUM CRISPUM, (Hass. ) Wittr. 



Oogonia single, obversely egg-shaped, opening with an 

 operculum, fissure narrow, oospores nearly globose, not 

 filling the oogonium 5 spermogonia 2-5 celled, hypogynous 

 or subepigynous ; sperrna'tozoids binate, terminal cell obtuse. 



Diameter veg. cells, 12-18 yw ; 2-4 times as long. 

 Diameter oogoii., 37-49 yu by 42-54 yu. 

 Diameter oospor., 33-46 yu by 34-46 //. 

 Diameter sperm, cells, 9-14 yw by 7-12 yw. 



Syn. Vesiculifera crispa, Hass. Oedog. rostellatum, Pringsh. 

 Oedoff. pulchellum, A. Br. 



Ponds and pools, Pennsylvania. 

 Plate LXXIY, fig. 15. ;_ 



Var. ROSTELLATUM. Pringsh. 



Agrees in all essential points with the type-form except 

 the terminal cell, not obtuse but rostellate. 



Meadow pools, ponds, etc. 



Plate LXXIV, fig. 11, young plant with oogonium, etc.; 

 fig. 12, first development from zoospore; figs. 13, 14, more 

 advanced stages. 



OEDOGONIUM PLUSIOSPORUM, Wittr. 



Oogonia single, subelliptic-globose ; opens by pore slightly 

 above the middle ; oospore globose, not quite filling the 

 oogonium ; spermogonia 2-6 celled, subepigynous, rare ; 

 terminal cell obtuse. 



