N Issued October 2S, 1007. 



U. S. DEPARTMENT OF AGRICULTURE 



BIOLOGICAL SURVEY- -BULLETIN No. 31 



C. HART MERRIAM, Chief 



AN ECONOMIC STUDY OF FIELD MICE 



(CtENUS MICROTUS) 



BY 



tJOiANlCAl, 



DAVID E. DANTZ 



Assistant, Biological Survey 



WASHINGTON 

 GOVERNMENT PRINTING OFFICE 



1907 



