VOL? El. 
Abund. 
Temperature 
Common 
Few 
Melosira 
Scarce 
Present 
Absent 
Abund. 
Common 
Few 
Synedra 
Scarce 
Present 
Absent 
Abund. 
Common 
Few 
Stephanodiscus 
Scarce 
Present 
Absent 
MINNESOTA BO’ 
Oct. Nov. Dec. Jan. Feb. Mi 
| | | 
FETT PEEP TTT PN hd hd he 
Pp} tet yt tN ee 
ASM, Se 
; ae 
et ELLE TTT TT 
cette tt LT | LE 
‘aa NSEREEREREREREAEES | CO 
RELY ALLTT TTT 
ole | | Nee TE eae 
PREECE 
+++ T\ Li ie 
TlLitlLitL_LlLi tlt ae 
Le TELL LLL LLL Lae 
ri tT TT LLL LL LLL ee 
pay ee et 
ilar Se, PN Stee eae 
SEAR 
eae NE A cess fe pe 
PLAT. 
THE HELIOTYPE PI 
