SMITHSONIAN MISCELLANEOUS COLLECTIONS. 

 MONOGRAPHS 



OF THE 



D I P T E R A 



OP 



NOETH AMERICA. 



PREPARED FOR THE SMITHSONIAN INSTITUTION 



BY 



H. L E W. 



PART I. 



EDITED, WITH ADDITIONS, 



BY 



R. OSTEN SAC KEN. 



WASHINGTON: 

 SMITHSONIAN INSTITUTION. 



APRIL, 1362. 



