100 FRESH-WATER ALG^ OF THE UNITED STATES. 



SECTION II. OOGONIA ELLIPSOID OR SUBELLIPSOID. 



OOSPORES OF SAME FORM AND FILLING THE OOGONIA ; EPISPORE 



LONGITUDINALLY COSTATE ; COST.E MORE OR 



LESS CRENULATE. 



SUBSECTION I. MONOECIOUS. 

 BULBOCHAETE MIRABILIS, Wittr. 



Oogonia ellipsoid or oblong-ellipsoid, patent or more rarely 

 erect, seated beneath a terminal seta or vegetative cell (or 

 aiidrosporangium) ; spermogonia 2-4 celled, erect, rarely 

 patent, subepigynons or scattered. Horizontal division of 

 vegetative cells not infrequent. 



Diameter veg. cells, 16-20 yw; li-lf times longer. 

 Diameter oogon., 27-35 /* by 46-56 yw. 

 Diameter sperm, cells, 10-12 /* by 7-9 /*. 



Have illustrated two forms (Plate LXXXVII, figs. 2, 3), 

 which I hesitatingly refer to this species, the former from 

 Minnetonka Lake, Minn., and from ponds, New Jersey; 

 the other (fig. 3) occurs now and then in ponds, New Jersey, 

 always sterile, hence perhaps valueless, but too distinct to 

 be entirely rejected. 



BULBOCHAETE NANA, Wittr. 



Oogonia ellipsoid, erect or patent, seated beneath terminal 

 setae or beneath vegetative cells ; spermogonia 1-2 celled, 

 subepigynous or scattered. 



Diameter veg. cells, 12-15 yw; 1-1 J times longer. 

 Diameter oogon. , 20-25 ^ by 33-36 //. 

 Diameter sperm, cells, 8-9 yu by 6-9 yw. 



Frequent in pond waters, New Jersey and elsewhere. Our 

 plant is equally near to B. Honile, Wittr., and B. nana, 

 Wittr. Have united the two and adapted the diagnosis. 



Plate LXXXVII, fig. 6. 



SUBSECTION II. DIOECIOUS. 



A. Dissepiment of supporting cells obsolete. 



BULBOCHAETE PYGMAEA, (Pringsh.) Wittr. 



Oogonia ellipsoid, patent, seated beneath a terminal seta 

 or beneath a vegetative cell ; in longitudinal section rather 

 quadrangular ; androsporangia scattered ; dwarf males seated 

 near the oogonia. Filaments often short and curved. 



