PEEFACE. 



Eight years ago the author of the present work published 

 a small volume in which he attempted to tabulate the families 

 and more important genera of the diptera of the United 

 States. From the use that has been made of that work by 

 entomological students, he has been encouraged to believe 

 that the labor of its preparation was not in vain. The extra- 

 ordinary activity in the investigation of our dipterological 

 fauna within the past few years has, however, largely destroy- 

 ed its usefulness, and it is hoped that this new edition, or 

 rather this new work, will prove as serviceable as has been 

 the former one. In the present work there has been an at- 

 tempt to include all the genera now known from north of 

 South America. While the Central and West Indian faunas 

 are preeminently of the South American type, there are doubt- 

 less many forms occurring in the southern states that are at 

 present known only from more southern regions. 



In the preparation of the work the author has been aided 

 by the examination, so far as he was able, of extensive col- 

 lections from the West Indies and Central America submitted 

 to him for study by Dr. D. Sharp of Cambridge, England, 

 and Messrs. Godman and Salvin of London, together with the 

 extensive collections of the University of Kansas and those 

 from South America in the author's private cabinet, alto- 

 gether forming probably the largest collection of American 



