THE GREEN ALGAE OF NORTH AMERICA 237 



ilium ; the aiithericlia are usually many in a series. Wolle's 

 reference appears to be the only authority for its occurrence in 

 America. 



20. OE. PALUDOSUM (Hass.) Wittrock, 1870, p. 124; Wolle, 

 1887, p. 74, PI. LXXV, fig. i ; Him, 1900, p. 120, PI. XIII, 

 fig. 69. Monoecious; oogonia single, ellipsoid, pore superior; 

 oospore ellipsoid, filling the oogonium, membrane triple, outer 

 and middle layers with longitudinal lines, 27-35 in number, con- 

 tinuous, rarely anastomosing ; antheridia i-8-celled, scattered, 

 often in the upper part of the filament ; spermatozoids binate, 

 division vertical. 



veg. cell, 15-20 fj. diain., 3-7 diam. long, 



oog., 39-48 fj. " 66-84 M long 



oos., 36-45 M " 54-63 M " 



anth. cell, 14-16 M " 6-13 /u. " 



Type reported by Wolle from Pa., but questioned by Him. 



Northern Europe. 



Var. AMERICANUM Norclstedt in Him, 1900, p. 121, PI. XIII, 

 fig. 72. Oogonia larger, ellipsoid; oospore of same shape, fill- 

 ing- the oogonium. 



veg. cell, 14-23 M diam., 3-7 diam. long, 



oog., 54-63 M " 75-9 M ! u g- 



oos., 49-57 M " 69-75 M " 



anth. cell, 12-18 p. " 7-12 (j. " 



So. Carolina. 



The peculiar sculpture of the spore is sufficient to distinguish 

 this and the following species from all others. The outer sur- 

 face of the external membrane is smooth, but its inner surface 

 and the outer surface of the median membrane are marked with 

 longitudinal lines, arranged like the meridians of a sphere. 

 The two species are distinct in the arrangement of the organs of 

 fructification, Oc. paludosum being monoecious, Oe. Boscii dioe- 

 cious. 



21. OE. BOSCII (LeCl.) Wittrock, 1870, p. 136; Wolle, 

 1887, p. 91, PI. LXXXII, figs. 11-13; Hirn, 1900, p. 122, PI. 

 XIII, fig. 73; Wittr., Nordst. and Lagerh., Alg. Exsicc., No. 

 1213. Dioecious; oogonia single (very rarely double) oblong- 

 ellipsoid, pore superior; oospore ellipsoid, not nearly filling the 

 oogonium ; marked as in Oc. paludosnui ; male plant somewhat 

 more slender than the female. 



