



y\ 



SMITHSONIAN MISCELLANEOUS COLLECTIONS. 



256 



MONOGRAPHS 



D I P T E R A 



NORTH AMERICA. 



/ 



PART III, 



PREPARED FOR THE SMITHSONIAN INSTITUTION 



BY 



H. LOEW. 



WASHINGTON: 

 SMITHSONIAN INSTITUTION. 



DECEMBEK, 1873. 



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