Trans. Wis. Acad., Vol. XI. Plate XXXII. 



0- 3 m Mch. Ape. May. June. July. Aug. Sept. Oct. Nov. Dec. 



200 







■A 

















100 







j 







^» ~ 















^s - 

















. 



6- 9 m 





9-12 m 



12-15 m 



" " » -"" r i ' ■ — • ' 



15-18 m 





Fig. 22.— Population of the 3 m. levels, 1895. Scale, 1 space = 100,000 Crusta- 

 cea. The 25.000 and 50,000 divisions are indicated. See page 387. 



