ovate, quadrangular-ovate, or spheroidal, formed between the 

 gametangia, the median wall yellow, brown, or blue, smooth or 

 variously ornamented; gametangia becoming filled with pectic 

 substances but without residues of cytoplasmic granules; reproduc- 

 tion also by aplanospores and akinetes. 



This genus is so much like Mougeotia in its vegetative expression 

 that identification cannot be made unless reproductive stages are 

 at hand. 



Key to the Species 



Zygospores lenticular, with 3 transverse ridges, 



S0-48fj, in diameter, 42-7 2/i long D. ghjptosperma 



Zygospores compressed-globose, median spore wall 



tricarinate, 50-54^ in diameter, 52-65/i long D. Ackleijana 



Deharya Ackleijana Transeau 1944, p. 244 

 Vegetative cells 12-15/i, in diameter, 90-140/* long; chloroplast an 

 axial ribbon with 8 pyrenoids; zygospores compressed-globose or 

 ovate, median spore wall with 3 ridges, the lateral ones rufiled and 

 with transverse corrugations between the ridges, middle keel lOju. 

 wide and radially striated, polar walls finely pitted, 50-54/a in 

 diameter, 52-65/a long. 

 Douglas Lake, Michigan. 



Deharya glyptospernia (DeBary) Wittrock 1872, p. 35 



Vegetative cells 9-1 6/t in diameter, 50-200/a long; chloroplast an 

 axial plate with several pyrenoids; zygospores lenticular or 

 compressed-ovate, median spore wall with 3 ridges which extend 

 as projections at the poles, the ridges interconnected by transverse 

 striations, 30-48|U, in diameter, 42-72/i long. 



Douglas Lake, Michigan. 



MOUGEOTIA (C. A. Agardh) Wittrock 1872, p. 35 



Unattached filaments of cylindrical cells without basal-distal 

 differentiation (rarely with lateral anchoring rhizoidal branches 

 near one end of the filament), forming entangled cottony masses, 

 floating or caught among aquatic plants, sometimes attached and 

 epiphytic on submerged culms of Scirpus, etc. Chloroplast occasion- 

 ally rod-like, usually a broad axial plate, sometimes 2 plates 

 connected by a bridge; with either an axial row of pyrenoids or 

 with pyrenoids scattered over the surface; sometimes twisted in 

 the midregion of the cell. Conjugation usually scalariform, the 

 zygospore formed in the tube between the gametangia; the zygo- 

 spore and tube sometimes enlarged so as to divide the gametangia, 



[297 ] 



