The True Flies 



Antennae rather short, never furnished with verticels of bristly 

 hairs, of the same structure in both sexes, eyes frequently 

 broadly contiguous above the antennae, but always sepa- 

 rated below it, pulvilli frequently well developed, body 

 rather robust (Super-family Bibionoidea) 1 1 



Super-family TIPULOIDEA Coq. 



4 — Thorax never furnished with a distinct V-shaped groove near 

 the middle of the upper side, discal cell always wanting 5 



Thorax furnished with such a groove, discal cell usually pres- 

 ent, mostly large flies, some of them the largest in this 

 subsection ; crane-flies Family Tipulidce. 



5 — Last subdivision of the veins which reach the wing-margin at 

 least nine in number, hind margin of the wings encom- 

 passed by a vein, tibiae never furnished with a pair of 

 spurs at the apex of the inner side 6 



Last subdivision of the veins which reach the wing-margin 

 not more than eight in number, tibiae sometimes furnished 

 with a pair of terminal spurs 8 



6 — Veins of the wings bearing long hairs or scales 7 



Veins bare, in the outer half of the wing three of the veins are 

 forked and there are two cross-veins ; rather large and 

 rare flies Family Dixidce. 



7 — Wings long and slender, the veins and body bearing flattened 

 scales ; mosquitoes Family Culicidce. 



Wings usually broad, like the body covered with long hairs ; 

 small, moth-like flies Family Psychodidce. 



8 — First two veins never coalescing and then separating into four 

 branches 9 



First two veins near their bases coalescing for a considerable 

 distance and then separating into four branches, the re- 

 maining vein forked ; rather small, very rare flies 



Family Stenoxenidce. 



9— Posterior margin of the wings encompassed by a vein, or the 

 tibiae furnished with a pair of long, apical spurs 10 



Posterior margin of the wings not encompassed by a vein, 

 tibiae never furnished with a pair of apical spurs, ocelli 

 wanting, antennae of the male frequently feather-like or 



with a pencil of long hairs Family Chironomidce. 



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