86 \!-:\V YoKK STATIC MTSEUM 



The wings are usually rather slender and delicate, with the 

 anterior veins (those nearest the costal border! rather stunt, 

 while the posterior \ein> are usualh \rry delicate and indistinct. 

 The surface of the wing is delicately hairy in a number of species, 

 though Hie majority have hare wings. 



lie low is given the ( "omstock -Needham terminology of wing 

 \enaiion as used in this paper, together with the equivalent terms 

 of the Srhinerian system as applied \\ith hut slight moditicat ions 

 to i he Nematocera generally : 



Comstock Needham ScLinorlati 



Costa (0) = Osia 

 Suhcosta (Sc) = Auxiliary 



Kadius i K , First longitudinal 

 K' = Second 

 K Third 



Media i.Mi - = Fourth 

 ruhitus (Cu) Fifth 

 Anal i.\ . : Sixth 



The cos ta ends at or lcfore the tip of the wing in all the 

 genera; the suhcosta. though sometimes rather indistinct, is 

 usually present; the radius is stout and \\rll developed, and 

 usually with two or three hram-hes, K_, in some genera appear- 

 ing like a crossvein ; the media usually present and always sim- 

 ple; the ciihitus is nearly al\\a\s two-branched: anal vein usually 

 present though delicate. Compare pi. 17, figs.UMi;, pls.1^7 to 31. 

 The halteres. the slender organs with knobbed ends which are 

 supposed to be the rudimentary second pair of wings, are rarely 

 wanting. 



For a description of the internal anatomy of both larva and 

 imago the reader is referred to Miall and Hammond's work on 

 the harlequin fly (1900). 



A large number of genera have been erected to contain the 

 species of the world. Of these some may be placed as the 

 synonyms of others, leaving still over 40 valid genera. In order 

 to facilitate identification a key to the North American genera 

 is offered besides the more general one for the genera of the 

 world. 



