THE GREEN ALGAE OF NORTH AMERICA 245 



superior ; oospore globose or subglobose, almost filling the 

 oogonium, membrane smooth; antheridium i-5-celled, subepi- 

 gynous or hypogynous ; spermatozoids binate, division hori- 

 zontal ; basal cell elongate, terminal cell obtuse. 



veg. cell, 12-16 /u. diam., 3-4% diam. long. 



oog., 37-45 M " 41-53 n long. 



oos., 35-43 n " 37-43 M " 



anth. cell, 8-14 /u. " 7-12 M " 



Greenland, Pa., Vancouver, Minn., Alaska, Cal. 



Europe, Asia, Africa, Australia, So. America, 

 Perhaps the commonest and most widely distributed species 

 of the genus, and including many varieties and forms, two of 

 which occur within our limits. 



Var. GRACILESCENS Wittrock in Wittr. and Nordst., Alg. 

 Exsicc., No. 509 ; Hirn, 1900, p. 162, PI. XXV, fig. 143 ; P. 

 B.-A., No. 518. Slender, oogonia and oospores varying in 

 form, oogonia oboviform-globose to oboviform-pyriform or sub- 

 ellipsoid, generally single, rarely 2 or 3 ; oospores globose to 

 ellipsoid. 



veg. cell, 10-14 M diam., 3-5 diam. long. 



oog., 33-39 /* " 33-5 1 M long. 



oos., 32-37 M " 33-42 n " 



anth. cell, 9-10 /u " 7-9 ^ " 



Mass., Minn., (Pa.?), Mo. So. America. 



The Pa. locality is surmised from Wolle's figure, which may 

 represent this variety, though given as Oe. vernale (Hass.) 

 Wittr. 



Var. URUGUAYENSE Magnus and Wille in Wille, 1884, p. 

 39, PI. II, fig. 63; Hirn, 1900, p. 164, PI. XXVI, fig. 145; 

 Wittr. and Nordst., Alg. Exsicc., No. 311, as Oe. crispum f. 

 typicum. Smaller, veg. cells shorter, oogonia single, subobovi- 

 form-globose ; oospore filling the oogonium ; antheridia subepi- 

 gynous, hypogynous or sometimes scattered. 



veg. cell, 10-14 /" diam., iK'3^2 diam. long. 



oog., 30-38 p " 33-43 Mlong. 



oos., 27-35 /* " 27-37 M ' 



anth. cell, 8-13 /* " 6-12 M ' 



p a . So. America. 



36. OE. OBESUM (Wittr.) Hirn, 1900, p. 166, PI. XXVI, 

 fig. 148. Monoecious; oogonia single, oboviform-globose, oper- 

 culate. division superior ; oospore globose, not quite filling the 

 oogonium, membrane smooth, often thickened ; antheridia i-2>- 



