DIPTERA 



OF 



NORTH AMERICA. 



PART II. 



VI. 



ON THE NORTH AMERICAN DOLICHOPODIDAE. 



INTRODUCTION. 



The Dolichopodidse are among those families of diptera which 

 show but so few points of relationship to others that it is impos- 

 sible to name any family of a particular affinity to them. A 

 superficial glance, it is true, seems to point out the Ephydrinidse 

 and the genera of the Tachydromidse in the vicinity of Clinocera 

 as the nearest to the Dolichopodidas • but a closer examination 

 will show that, instead of a true relationship, there are merely 

 some points of external analogy between them, points common 

 to most insects (and not only diptera) preferring to live in the 

 vicinity of water. The want of a true relationship becomes 

 immediately apparent when any portion of their inner or outer 

 organization is submitted to a comparative scrutiny. The neura- 

 tion of the wings of the Dolichopodidse alone is so peculiar that 

 it is sufficient in itself to distinguish this family not only from 

 the Ephydrinidse and the above-mentioned group of Tachydro- 

 midse, but also from all other families of the order. This neura- 

 tion, together with the brilliant-green color of the greater part 

 of the species, renders the Dolichopodidse one of the most easily 

 recognizable families of diptera. 



The peculiarities of the neuration, which is shaped in general 

 1 



