SMITHSONIAN MISCELLANEOUS COLLECTIONS. 



171 



MONOGRAPHS 



OF THE 



D I P T E R A 



OF 



NORTH AMERICA. 



PREPARED FOR THE SMITHSONIAN INSTITUTION 



BY 



H.' LO E W. 



PART II. 



EDITED BY 







K. OSTEN SACKEN, 



WASHINGTON: 

 SMITHSONIAN INSTITUTION. 



JANUARY, 1SS4. 



