Issued October 28, 1007. 



U. S. DEPARTMENT OF AGRICULTURE 



BIOLOGICAL SURVEY— BULLETIN No. 31 



C. HART MERRIAM, Chief 





N0V1 1907 



AN ECONOMIC STUDY OF FIELD MICE 



(GENUS MICROTUS) 



BY 



DAVID E. LANTZ 

 Assistant, Biological Survey 





WASHINGTON 

 GOVERNMENT PRINTING OFFICE 



1907 



