NEMATOCERA. 



Discal cell always absent. Head in 

 male dichoptic (eyes separated). 

 Antenna filiform, the apical part indi- 

 visible into exact joints Dixidae. p. 257. 



5. Wings with scales. Legs long and 



slender. Proboscis always long, stiff, 

 conspicuous, formed expressly for 

 biting (except Corethra). Palpi long, 

 stiff', prominent (except Corethra) .... Culicidas. 

 Wings with hairs (in some species also 

 with small white spots composed of 

 scales*). Legs short and compara- 

 tively stout. Proboscis, without being 

 so long and conspicuous, elongate and 

 horny in Phlebotomits, formed for 

 biting, and in some PSYCHODINJE, 

 though short, capable of piercing the 

 skin. Palpi short, incurved Psychodidae, p. 196. 



6. Legs short and stout (about the same as 



in the BRACHYCERA). Head in male 

 holoptic. Antennae short and com- 

 paratively stout, shorter than thorax . 7. 

 Legs normally long and slender (except 

 only in Orphnephila). Head in male 

 dichoptic (except in one or two genera 

 of MYCETOPHILHXS:). Antennae long 

 and slender (except in Orphnephila), 

 often longer than the head and thorax 

 taken together 8. 



7. The 2nd basal cell and the posterior 



cross-vein present. All veins distinct 

 (BiBiONiNJE).t Wings normally broad, 

 costal vein extending round the mar- 

 gin of the wing. Ocelli present. 



Antennae short and stout Bibionidae, p. 157. 



The 2nd basal cell always present; 

 posterior cross-vein always absent. 

 Auxiliary, 1st and 3rd longitudinal 

 veins thickened, the rest generally 

 faint. Wing distinctly broader than 

 usual. Costal vein ending at tip of 

 wing. Ocelli absent. Antennas long, 

 slender, typically nematocerous Simuliidae, p. 182. 



8. Antennae apparently of three joints, 



terminating in a bristle. Wing with 

 two basal cells. Legs comparatively 



short ". Orphnephilidae 



Antennae normally uematocerous. (not Oriental). 



Wing with only one basal cell (except 

 in one or two genera of BLEPHARO- 

 CERIDJE). Legs long and slender . . 9. 



43 



* In a few species the wing itself is more or less covered with small scales, 

 in addition to or irrespective of such spots. 



t When the 2nd basal cell and the posterior cross-vein are absent, the 

 longitudinal veins are always very indistinct (ScA 



