82 FRESH-WATER ALGJE OF THE UNITED STATES. 



Diameter androsp. cells, 26-28 /< by 30-36 p. 

 Diameter stipe dwarf male, 20-25 ^ by 55-75 ^. 

 Diameter sperm, cells, 10-12 /* by 22-25 //. 



Syn. Vesiculifem concatenate, Hass. ; Oe. a/pophysatum, Pringsh. 



Frequent in Pennsylvania, New Jersey and probably in 

 every State. 



Plate LXXIX, figs. 1, 2, filaments with oogouia, dwarf 

 males, androsporangia, etc. ; fig. 3, an outline of a series of 

 quadrangularly ellipsoid oogonia. 



Var. SETIGERUM, (Vaup.) Wolle. 



A plant which bears a very close relation to Oe. concate- 

 natum except that the terminal cell is not obtuse but bears 

 a long seta. 



Ponds, Northampton County, Pennsylvania. 



Plate LXXIX, figs. 4 and 5, parts of two filaments show- 

 ing the setae. 



OEDOGONITJM SEXANGULARE, Cleve. 



Gynandrosporuos ; oogonia single, rarely twin, sexan- 

 gular- ellipsoidal, open by a pore slightly above the middle ; 

 oospore nearly filling the oogoniuin; androsporangia 2-4 

 celled ; dwarf males somewhat curved, seated on the sup- 

 porting cells ; spermogoniuni one- celled. 



Diameter veg. cells, 9-16 /*; 3J-7 times longer. 

 Diameter oogon., 29-32 /u by 33-38 /. 

 Diameter oospor., 27-30 fA, by 31-36 //. 

 Diameter androsp. cells, 13-14 /* by 10-14 /*. 

 Diameter stipe dwarf male, 7-9 ^ by 21-27 p. 

 Diameter sperm, cells, 6-7 yw by 9-12 yw. 



A widely distributed species. 



Plate LXXIX, figs. 8, 9, a filament with oogonia, dwarf 

 males and androsporangia. 



OEDOGONIUM WOLLEANUM, Wittr. 



Idio-androsporous ; oogonia single, or 2-5, rarely ten, 

 seriate, elliptic or oval; oospore oval, nearly filling the 

 oogoniuni ; more or less densely, longitudinally, costate ; 

 androsporangia 6-10 celled ; dwarf males somewhat curved, 

 seated on the supporting cells sperrnogoiiia 1-4 celled ; 

 supporting cells somewhat tumid ; oogoniuin often terminal. 



