THE GREEN AIGAE OP NORTH AMERICA 241 



Resembles Oe. Landsboroughii, but the latter is dioecious. 



27. OE. L/ANDSBOROUGHII (Hass.) Wittrock, 1874, p. 35; 

 Wolle, 1887, p. 91, PI. LXXXI, figs. 8-n; Him, 1900, p. 

 135, PI. XVI and XVII, fig. 94; P. B.-A., No. 663. Dioe- 

 cious; oogonia single, rarely 2, oboviform or suboboviform, 

 pore superior ; oospore oboviform to ellipsioid, filling or not 

 quite filling the oogonium, membrane smooth ; male plant gen- 

 erally a little more slender than the female ; antheridia to 25- 

 celled ; spermatozoids binate, division vertical ; basal cell 

 elongate, apical cell obtuse. 



veg. cell, female, 31-40 /u. diam., 3-6 diam. long. 



veg. cell, male, 30-37 v- " 4-6 



oog., 63-75 fj. " 85-110^ long. j 



oos., 59- 7 M " 73-102 M " 



auth. cell, 27-35 /u " 9-20 n " 



Mass., Conn., N. Y., Mexico. Europe, So. America. 



A widely distributed species, and varying somewhat, but not 

 as much as some other species ; a form has been found in Mex- 

 ico with veg. cells 37-51 / diam., otherwise like the type.* 



28. OE. OBOVIFORME Wittrock, 1878, p. 140; Him, 1900, 

 p. 141, PI. XX, fig. 103. Dioecious; oogonia single, obovi- 

 form, pore superior; oospore oboviform, about filling the 

 oogonium, rarely ellipsoid-oboviform, and then not quite filling 

 the oogonium, membrane smooth ; male plant about the same 

 size as the female ; antheridia to ig-celled ; spermatozoids 

 binate, division vertical ; basal cell elongate. 



veg. cell, female, 21-33 /a diam., 3/^-9 diam. long, 



veg. cell, male, 21-31 /x " 3/4-9 



oog., 55-65 fj. " 80-107 fj. long, 



oos., 54-61 ij. " 70-85 M " 



anth. cell, 21-28 /j. " 5-13 /* " 



Vera Cruz, Mexico. So. America. 



Quite close to Oe. grande, but distinguished by the obovi- 

 form oogonia. 



29. OE. PACHYANDRIUM Wittrock in Wittr. and Nordst., 

 Alg. Exsicc., No. 5 ; Wolle, 1887, p. 89, PI. LXXV, figs. 9 

 and 10 ; Hirn, 1900, p. 142, PI. XX, fig. 104. Dioecious; 

 oogonia single or rarely 2, very rarely 3, suboboviform or 



*Wolle, 1887, p. 92, PL I/XXVI, figs. 7 and 8, describes anew var. major 

 of Oe. rivulare (L,eCl.) A.Br.; Hirn, 1887, p. 141, thinks that this may 

 belong under Oe. crassum, forma amplum (Magn. & Wille) Hirn ; re- 

 sembling Oe. Landsboroughii, but of larger dimensions; the dimensions 

 given by Wolle are, however, larger than anything recorded for any form 

 of Oe. crassum. 



