150 WISCONiSIN I'HYTOPLANKTON 



PLATE 53. 



All figures x 400. 



Page 



Fig. 1. Closterium acerosum (Schrank) Ehr 10 



Fig. 2. Closterium gracile var. elongatum W. & G. S. West 11 



Pig. 3. Closterium aciculare var. suhpronum W. & G. S. West. 11 



Pig. 4. Closterium acutum (Lyngb.) De Breb 11 



Pig. 5. Closterium Ealfsii var. hybridum Kab 12 



Pig. 6. Closterium Kuetsingii De Breb 12 



Pig. 7. Closterium decorum De Breb 13 



