June, 1921] 



Neiv Forms of Ocdogonium 



273 



In appearance this species is near Oedogonium cyathigeriim 

 Wittr. It differs, however, in being macrandrous, in having a 

 smaller number of ribs, and in having the ribs on the outer wall 

 instead of the inner wall of the oospore. It is easily distin- 

 guished from Oedogonium crenidato-costatiim Wittr. by its 

 swollen suffultory cells, its spore markings, and its larger 

 dimensions throughout. Among the operculate species it bears 

 some resemblance to Oedogonium pauco-costatum Transeau. 



Found rather abundant in Dollar Lake and Summit Lake, 

 near Akron, Ohio, August, 1920. Type in L. H. T. collections, 

 Nos. 196, 198. Plate I, Fig. A-F. 



Oedogonium p^uco-costatum Transeau var. gracilis nov. var. 



Var. omnibus partibus gracilior; oosporis ellipsoideis vel globoso- 

 ellipsoideis, oogonia fere complentibus vel non complentibus ; ceterum 

 ut in typo; 



Crassit. cell. veg. 

 Crassit. oog. 

 Crassit. oos. 

 Crassit. cell, antherid. 



15-20 M altit. 66-120 At 



48-52 u. altit. 70-88 m 



44-48 M altit. 60-70 m 



17-20 M altit. 8-12 m 



Somewhat smaller than the species; the oospore is ellipsoid or 

 occasionally globose-ellipsoid, completely filling the oogonia or not 

 filling the oogonia; otherwise similar to the type; 



Diam. veg. cells 

 Diam. oogonia 

 Diam. oospore 

 Diam. antheridial cells 



15-20 M length 66-120 n 



48-52 M length 70-88 fj. 



44-48 M length 60-70 fj. 



17-20 M length 8-12 fx 



This variety bears some resemblance to Oedogonium Aus- 

 traliamim Hirn. It differs, however, in having largely ellip- 

 tical oospores, in the similarity of the vegetative cells of the 

 male and female filaments, and in the smaller number of ribs 

 on the median spore walls. It seems most closely related to 

 Oedogonium pauco-costatum Transeau in its general habit of 

 growth. It was found associated with Oedogonium taphro- 

 sporum Nordst. and Hirn. 



Collected at Turkeyfoot Lake near Akron, Ohio, August, 

 1920. Type in L. H. T. collections Nos. 177, 182. 



