VOL. II. MINNESOTA B: 
Oct. Nov. — Dec. Jan. Feb. | 
Common 
Few 
Coelosphaerium 
Scarce 
Present 
BEN 
Absent 
Abund. 
Common 
Few 
ghee eaant atone 
Scenedesmus Pasta oie fade eer a a ee 
Scarce RE 
Present 
Absent 
Abund. 
Common 
Few 
Oscillatoria 
Scarce 
Present 
Absent 
PLAT 
THE HELIOTYPE 
