80 FRESH-WATER ALG^ OF THE UNITED STATES. 



OEDOGONIUM MACRANDRIUM, Wittr. 



Oogonia single or 2-3 seriate, egg-shaped or globose egg- 

 shaped, opening by an operculum, fissure very narrow ; 

 oospore globose or egg-shaped globose, not filling the 

 oogonium ; terminal cells apiculate ; dwarf males much 

 curved, seated on the oogonium, stipes often 2-3 celled ; 

 spermogonia two or more, often seven-celled. 



Diameter veg. cells, 15-16 yu; 3-5 times longer. 

 Diameter oogon., 36-40 // by 43-54 yw. 

 Diameter oospor., 31-34 yu by 33-39 yw. 

 Diameter stipe dwarf males, 12 yw by 24-33 //. 

 Diameter sperm, cells, 9 jn by 5-9 yu. 



Marsh grounds, Eastern Pennsylvania. 

 Plate LXXXII, figs. 1, 2, 3. 



OEDOGONIUM CRASSIUSCULUM, Wittr. 



Idio-androsporous or gynandrosporous ; oogonia single or 

 binate ; globose egg-shaped or nearly globose, opening by a 

 pore above the middle ; oospore ellipsoid-globose or obverse 

 egg-shaped globose, membrane thick, nearly filling the oogo- 

 nium ; androsporangia 2-6 celled ; dwarf males straightish, 

 seated on or about the supporting cells ; spermogonia 1-2 or 

 more celled. 



Diameter veg. cells, 27-30 yw ; 31-5 times longer. 

 Diameter oogon. , 54-60 yw by 60-75 yu. 

 Diameter oospor., 51-57 yw by 52-63 yu. 

 Diameter androsp. cells, 26-28 yw by 10-18 yw. 

 Diameter stipe dwarf males, 13 yw by 60 yu. 

 Diameter sperm, cells, 7-9 yw. 



Not infrequent ; had good fruiting specimens from Penn- 

 sylvania, New Jersey and Minnesota, all idio-androsporous. 

 No doubt widely distributed. 



A specimen from Northern New Jersey presented an 

 unusual appearance, an oogonium swarming in the space be- 

 tween the wall of the oogonium and the oospore with small 

 spermatozoid-like cells, most numerous in the upper part of 

 the oogonium, passing in and out through the pore. Their 

 function was not evident; if spermatozoids, their number 

 was extraordinary. In the course of 8-10 minutes they 

 gradually disappeared. 



Plate LXXYII, figs. 14, 15, 16, sections of filaments. 

 Fig. 17, the oogonium referred to in the last lines. 



