Key to the Species 



1. Cells oblong or ovate 2 



1. Cells spherical — 3 



2. Colony triangular or pyramidal; individual cell sheaths distinct 



and much lamellated - — G. planctonica 



2. Colony ovate or amorphous 4 



3. Colony spherical, usually of 8 cells (sometimes solitary), the 



colonial mucilage and cell sheaths regularly lamellate G. gigas 



3. Colony amorphous, forming irregularly expanded, jelly-like masses, 



often attached; colonial mucilage lamellate G. vesiculosa 



4. Cells many in a colony; individual cell sheaths distinct, angular 



from mutual compression, not lamellate G. ampla 



4. Cells few in a colony; sheaths lamellate G. major 



Gloeocystis ampla ( Kuetz. ) Lagerheim 1883, p, 63 



PI. 3, Fig. 17 



Cells ovoid or oblong, arranged in amorphous or somewhat globu- 

 lar colonies and embedded in copious unlamellated gelatinous en- 

 velopes, the sheaths of each cell or group of cells not confluent but 

 distinct and angular from mutual compression. Cells 9-1 Iju, in 

 diameter, 10-14/a long; colonies up to 150/x in diameter. 



Common in the tychoplankton of many soft water lakes and acid 

 swamps. Mich., Wis. 



Gloeocystis gigas (Kuetz.) Lagerheim 1883, p. 63 

 PI. 3, Fig. 16 



One-celled or a colony of 8 spherical or slightly oblong individuals 

 inclosed by a copious, gelatinous, lamellate envelope. Contents of 

 the cell frequently brownish-green because of oil. Cells 9-1 2ju, in 

 diameter. Forming gelatinous masses on submerged aquatics or 

 entangled among other algae. 



Common in the tychoplankton of many lakes and swamps. Mich., 

 Wis. 



Gloeocystis major Gerneck ex Lemmermann 1915, p. 35 



PI. 52, Figs. 9, 10 



Cells ovoid, in colonies of 4-8, inclosed by a wide, lamellate sheath 

 in which groups of individuals are surrounded by concentric layers; 

 Chloroplast massive, completely covering the wall; cells 17-19/x in 

 diameter, 21-23/x long. 



Tychoplankter; in hard water lakes. Wis. 



[84] 



