understood genus and rather rare, although some species seem to 

 be widely distributed. There appears to be some confusion in the 

 records of the plants assigned to the type species, G. Nostochin- 

 earum. Evidence at hand appears to warrant the separation of 

 spherical from elliptical plants and the assignment of only the latter 

 to the type species if they possess vermiform, radiating 'chromato- 

 phores.' See Geitler (1923a) and Hieronymus (1892a) on the 

 morphology of these plants. 



Key to the Species 

 1 . Cells ellipsoidal 2 



1. Cells spherical G. duplex 



2. Cells broadly elliptical with nodular thickenings 



at the poles G. oocystiformis 



2. Cells elliptical, without nodular thickenings 



at the poles G. Nostochinearum 



Glaucocijstis duplex Prescott 1944, p. 371 

 PI. 108, Fig. 1 



Colony composed of 8-16 spherical cells inclosed by a much 

 enlarged spherical mother cell wall; chromatophore-like bodies in 

 the form of 2 stellate masses with long or short vermiform blue- 

 green protoplasts radiating from 2 separate points; cells 40-44/i, in 

 diameter; colony 150-170/i, in diameter. 



This species differs from G. Nostochinearum by its spherical shape 

 and by the dual arrangement of the colored protoplasts. From G. 

 cingulata Bohlin it differs in the morphology of the cell wall. In 

 that species the cells are spherical, but the wall has a median an- 

 nular thickening. The chromatophores are numerous and parietal. 

 Some forms of G. Nostochinearum are described as spherical, but 

 other features which they possess seem to warrant the assignment 

 of the Wisconsin plants described above to a different species. 



Among dense clots of algae in Manitowish River, Wisconsin. 



Glaucocystis Nostochinearum ( Itz. ) Rabenhorst 1868, p. 417 



PI. 108, Fig. 2 

 A free-floating colony of 4-8 elliptical cells inclosed by the old 

 mother cell wall; chromatophores axial and stellate in arrangement, 

 bright blue-green; host cell reproducing by autospore formation; 

 cells 10-1 8/u, in diameter, 18-23.4- (28)//, long; colony of 4 individ- 

 uals up to 50/x long. 



Intermingled with miscellaneous algae in soft water ponds and 

 acid swamps; especially common in desmid habitats. Wis. 



[474] 



