Because of their minute size they may easily be mistaken for a 

 colony of bacteria. Their faint bluish-green pigmentation is scarcely 

 to be differentiated from the apparently similar color of unstained 

 bacteria caused by light refraction in microscopical examination. 

 The name A. saxicola Naeg. is used tentatively for this small plant. 

 It is nearest A. nidulans P. Richt. in size but is more slender and 

 the cells are more loosely arranged in the colonial mucilage than 

 described for A. nidulans. According to Drouet and Daily (I.e.) 

 Aphanothece saxicola is synonymous with Anacijstis marginata Men- 

 eghini, the original description of which does not agree with our 

 specimens. The former name is used here, therefore, to refer to a 

 plant which agrees with the description of A. saxicola. 

 In Sphagnum bogs; tychoplankter in lakes. Mich., Wis. 



Aphanothece stagnina ( Spreng. ) A. Braun in Rabenhorst 



1864-1869, Algen No. 1572 



[Anacystis rupestris (Lyngb.) Drouet & Daily in Daily 1942, p. 650] 



PI. 103, Figs. 14-16 

 Cells short cylindric, evenly distributed throughout an ovate or 

 irregularly globose gelatinous mass; colonies bright green, attached 

 and attaining macroscopic size; cell contents usually bright blue- 

 green (sometimes pale), homogeneous; cells sheaths diffluent and 

 not evident; cells 3.7-7/a in diameter, 5-8ja long. 



Free-floating colonies with larger cells are usually referred to 

 Aphanothece prasina A. Braun. In his treatment of the genus, Daily 

 has assigned the name Anacystis rupestris var. prasina (A. Braun) 

 Drouet & Daily to this form and does not separate it from Aphano- 

 thece stagnina ( Spreng. ) A. Braun. 



Common in many lakes; usually in shallow water; often forming 

 almost continuous gelatinous expanses on the bottom of favorable 

 eutrophic habitats. Mich., Wis. 



COELOSPHAERIUM Naegeli 1849, p. 54 

 A free-floating, globular, ovate, or irregularly shaped colony of 

 spherical or subpyriform cells arranged in the colonial mucilage, in 

 a single peripheral layer, producing a hollow sac; cell contents pale 

 to bright blue-green, either homogeneous or with numerous refrac- 

 tive pseudovacuoles; colonial envelope homogeneous, or with radiat- 

 ing, gelatinous fibrils. 



This genus should be compared with Aphanocapsa, in which the 

 cells are scattered throughout the colonial mucilage. 



[469] 



