THE GREEN ALGAE OF NORTH AMERICA 231 



a stouter aspect, and almost ellipsoidal oogonia. Oc. cardiacuni 

 has two spermato/oids in each antheridial cell, the others one 

 spermatozoid only. 



6. OE. PLUSIOSPORUM Wittrock, 1874, p. u ; Wolle, 1887, 

 p. 72, PI. LXXIV, figs. 20 and 21; Him, 1900, p. 84, PI. II, 

 fig. 17. Monoecious; oogonia single, subglobose or ellipsoid- 

 globose, pore slightly above the middle ; oospore globose or 

 nearly so, not quite filling the oogonium, membrane smooth ; 

 antheridia up to 6-celled, subepigynous, subhypogynous, or 

 scattered ; spermatozoid single ; terminal cell obtuse. 



veg. cell, 12-19 M diam., 2 -4 diam. long, 



oog., 34-45 /j, " 35-50 fj. long, 



oos., 30-39 p. " 30-39 M " 



anth. cell, 12-14 M " 8-12 M " 



Pa., N. J., Cal. Northern Europe. 



7. OE. CARDIACUM (Hass.) Wittrock, 1870, p. 135; Him, 

 1900, p. 85, PI. Ill, fig. 19. Dioecious; oogonia single, very 

 rarely 2, subglobose or subcordiform-globose, pore slightly 

 above the middle ; oospore globose, not filling the oogonium, 

 membrane smooth ; male plants slightly more slender than 

 the female ; antheridia up to lo-celled, spermatozoids binate, 

 division horizontal ; basal cell elongate, terminal cell obtuse. 



veg. cell, female, 18-30 /j. (Ham., 3-7 diam. long. 



veg. cell, male, 15-25 /" " 3-7 " 



oog., 48-70 fj. " 58-78 M long. 



oos., 42-60,11 " 42-60 /a " 



anth. cell, 15-21 /a " 10-14 M " 



Pa., Ontario. Europe, Africa, So. America. 



The range in dimensions is considerable ; in most cases the 

 plants approach the lower limit, only rarely the upper. 



Var. CARBONICUM Wittrock, in Wittr. and Nordst., Alg. Ex- 

 sicc., No. 504; Him, 1900, p. 87, PI. IV, fig. 22, is reported 

 from Iowa by Wolle, 1887, p. 90, PI. lyXXXII, figs. 14 and 15. 

 It has oogonia not uncommonly double, oboviform or globose- 

 oboviform, pore higher than in the type, oospore the same form 

 as the oogonium, and not quite filling it. 



8. OE. FRANKLINIANUM Wittrock, in Wittr. and Nordst., 

 Alg. Exsicc., No. 309; Wolle, 1887, p. 89, PL LXXXII, figs. 

 7-9; Him, 1900, p. 88, PI. II, fig. 18. Dioecious; oogonia 

 single (very rarely 2), subglobose (or sub-ellipsoid-globose), pore 

 superior ; oospore globose, almost filling the oogonium, mem- 

 brane smooth ; male plant rather more slender than the female ; 

 antheridia i-3-celled ; spermatozoids 2, division horizontal. 



