Oscillatoria ctirviceps C. A. Agardh 1824, p. 68 

 PI. 108, Figs. 17, 18 

 Trichomes forming an expanded blue-green plant mass; straight 

 for at least a portion of tlieir length, twisted and much entangled, 

 scarcely tapering to the apex. Apical cell broadly rounded, not 

 capitate, without a calyptra. Cells 10-14-(17)/a in diameter, 3-5/x 

 long; not constricted at the cross walls, which may be granulate. 

 Forming floating clots; tychoplanktonic. Mich., Wis. 



Oscillatoria formosa Bory 1827, p. 474 

 PI. 109, Figs. 10, 11 

 Trichomes aggregated to form a dark blue-green plant mass; 

 straight and rather firm, curved and slightly tapering toward the 

 apex. Apical cell conical, not capitate, without a calyptra. Cells 4-6/i, 

 in diameter, 2.5-5/x long; constricted at the cross walls, which 

 are granular. 



Rather common on wet soil at margins of lakes, and about 

 swamps; tychoplanktonic in shallow water of ponds. Mich., Wis. 



Oscillatoria granulata Gardner 1927, p. 37 

 PI. 109, Figs. 12, 13 

 Trichomes aggregated to form an expanded plant mass; straight 

 or somewhat curved, especially at the apex, which is slightly atten- 

 uated. Apical cell not capitate and without a calyptra. Cells 3-5/a 

 in diameter, 1/2-1 Vo times their diameter in length; not constricted 

 at the cross walls, which are distinctly granular. 



Occurring as small, slimy flakes, or scattered among other algae. 

 Wis. 



Oscillatoria Hamelii Fremy 1930, p. 218 

 PI. 109, Fig. 14 



Trichomes solitary among other algae, or sparsely aggregated to 

 form blue-green masses; straight or undulate, not attenuated at the 

 apices. Apical cell truncately conical, without a calyptra. Cells 

 7.2-8.5/x in diameter, 11/3-2 times the diameter in length; distinctly 

 constricted at the cross walls, which are not granular. 



This plant is assigned here on the basis of its agreement with 

 Fremy's description. The type habitat of O. Hamelii is in Africa, 

 but the universal distribution of many species of the genus makes 

 its appearance in North America not unusual. 



Forming a film on dead leaves in a stream. Wis. 



[487] 



