PREFACE. 



That which has been aimed at in the present Synopsis is the descrip- 

 tion, as full and complete as possible, of the North American Syrphidse, 

 The labor involved in the determination of our diptera, save such as 

 have been described or monographed by Dr. Loew and Baron Osten 

 Sacken, is very great, owing to the often incomplete and unsatisfactory 

 descriptions scattered through the literature of a half dozen languages. 

 To bring together descriptions in such a way as will render the identi- 

 fication of our numerous species less toilsome and more certain, is the 

 only means that will now materially further the study of American 

 diptera ; the descrii)tion of desultory new species is detrimental to real 

 progress in the knowledge of our fauna. My aim has been the study 

 of genera and species, to so describe and figure those of the United 

 States as to render them more easily determinable. With every page I 

 write I feel more fully how diflflcult descriptive dipterology really is, and 

 that only a beginning has been made in the studj^ of this interesting 

 family. But the work will, I trust, serve a useful purpose in pointing 

 out what the needs and necessities are, and to pave the way for a future 

 exhaustive monograph of the family, based upon a wider knowledge than 

 is now possible. 



I have given especial attention to this family since the beginning of 

 my dipterological studies eight years ago, and have collected a large 

 part of the species, either in New England or the West. I ex)uld not, 

 however, have accomplished what I have, except by the aid of tlie many 

 friends who have kindly sent me material. Without in any way depre- 

 ciating the favors of others, I would express my acknowledgments es- 

 pecially to Prof. J. H. Comstock, of Cornell University, for the aid fur- 

 nished me in the examination of a C9nsiderable collection, among which 

 I found the very interesting genus Senogaster ; to Mr. Eugene L. Keen, 

 of Philadelphia, who, in the most generous wa^^, gave me freely every- 

 thing I desired from bis industrious collecting ; to Prof. C. V. Riley, of 

 Washington, for the privilege of examining his large collections, in- 

 cluding the excellent one of Mr. E. Burgess; and to Mr. D. W. Coquil- 

 lett, of Anaheim, Gal., Mr. Theodore Pergande, of Washington, D. C, 

 and Dr. George Dimmock, of Cambridge, for the addition of not a few 

 q[>ecies otherwise unknown to me. Other aid has been afforded me by 



