THE GREEN AI.GAE OF NORTH AMERICA 263 



2-3, subdepressed-globose, operculate, division median, rather 

 narrow ; oospore subdepressed or depressed-globose, almost fill- 

 ing the oogonium, membrane smooth ; suffultory cell not 

 swollen ; androsporangia to 6-celled, subepigynous, hypogy- 

 nous or scattered ; dwarf males obovifortn, unicellular, on 

 the oogonium. 



veg. cell, 9-12 fj. diam., 3-5 diam. long, 



oog., 30-38/1* " 27-40 /j. long, 



oos., 25-34 /j. " 23-28 n " 

 andr. cell, 9-10 /u " 8-15 /u " 



nan. cell, 6-7 /j. " 13-15 M " 



N. J., Iowa. Europe. 



Somewhat resembling Oe. Rothii, but a larger plant. 



67. OE. ARESCHOUOII Wittrock, 1870, p. 122, PI. I, figs, i 

 and 2 ; Wolle, 1887, p. 76, PI. LXXVII, fig. 7 ; Him, 1900, p. 

 270, PI. XI/VI, fig. 289. Dioecious, nannaudrous, gynaudro- 

 sporous ; oogonia 2-6 or single, subdepressed- or depressed- 

 pyriform-globose, operculate, division median, broad ; oospore 

 globose, rarely subdepressed-globose, not nearly filling the 

 oogonium, membrane smooth ; suffultory cell of the same form 

 as the other vegetative cells; androsporangia i -6-celled, sub- 

 epigynous or hypogynous, or more rarely scattered ; vegetative 

 cells capitellate ; basal cell elongate, terminal cell, which some- 

 times is an oogonium, obtuse ; dwarf males oboviform, unicel- 

 lular, on the oogonium. 



veg. cell, 8-13 M diam., 4-6 diam. long, 



oog., 34-39 M c< 36-40 M long, 



oos., 22-26 M " 22-25 /j. " 



andr. cell, 9-11 n " 10-12 /a " 



nan. cell, . 6-7 M " 13-15 M " 



Greenland, N. J. Europe, So. America. 



Forma ROBUSTUM Him, 1900, p. 271, PI. XL,VI, fig. 290. 

 Idioandrosporous ; larger in all parts than the type, especially 

 as to the vegetative cells ; oogonia to 8-seriate. 



veg. cell", 12-17 M diam., 3-6 diatn. long, 



oog., 36-40 M " 3 6 -53 M long, 



oos., 30-32 n " 27-31 M " 



andr. cell, 9-12 M " 10-13 M " 



nan. cell, 6-8 M " 14-15 /a " 



England. 



Him includes provisionally under this form the plant from 

 Minnesota, distributed in Tilden, American Algae, No. 3, as 



