SMITHSONIAN MISCELLANEOUS COLLECTIONS. 

 MONOGRAPHS 



D I P T E R A 



NORTH AMERICA. 



PREPARED FOR THE SMITHSONIAN INSTITUTION 

 BY 



II . L E W. 



PART I, 



EDITED, WITH ADDITIONS, 



B. OSTEN SACKEN. 



WASHINGTON: 

 SMITHSONIAN INSTITUTION. 



APRIL, 18G2. 



C/ 



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