Trans. Wis. Acad., Vol. XI. 



Plate XXXIII. 



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



4UU 



300 

 200 

 100 











\^ _ 























V: 





/\~ 



















\ - 



/ 







"" _ 















- 





--• - 



9-12 m 



12-15 m 



15-18 m 



Fig. 23. — Population of the 3 m. levels, 1896. Scale, 1 vertical space 

 = 100,000 Crustacea per sq. meter. See p. 387. 



