FIELD BOOK OF INSECTS. 



21. Vertex flat or convex, the eyes not bulging; in the 

 males the eyes often contiguous 22. 



Vertex sunken, distinctly hollowed out between the 

 eyes, which are never contiguous in the males. Mostly 

 large flies 24. 



22. Fourth longitudinal vein terminating at or before the 

 tip of the wing. Three posterior cells. Proboscis hidden. 

 Antennas without a style or bristle. Flies of moderate 

 or small size, bare or scaly SCENOPINID/E 



(p. 250). 



Fourth longitudinal vein terminating beyond the tip 

 of the wing. Antennae often with a terminal style. Body 

 usually bristly or pilose, sometimes of large size. Proboscis 

 projecting 23. 



23. Five posterior cells in the wing. Abdomen rather 



long and tapering. Proboscis moderately long 



THEREVID^E (p. 250). 



As a rule, 4 or 3 posterior cells in the wing. Abdomen 

 usually stout, broad, hairy, rarely very slender and bare. 



Proboscis often very long BOMBYLIID^; 



(p. 250). 



24. 'Body without bristles. Proboscis with fleshy 

 labella at tip. Venation of the wing complicated, the 

 fourth longitudinal vein curves forward to terminate in 

 front of the wing-tip MYDAID^E 



(p. 251). 



Body bristly. Proboscis horny and rigid, without 

 fleshy labella at tip. Venation of the normal type. . . . 

 ASILID.E (p. 251). 



25. Wings pointed; no cross-veins except at the base; 

 second longitudinal vein ending almost at the tip of the 

 wing. Length, less than .2 in LONCHOPTERID.E. 



Wings rounded at the tip, the second longitudinal 

 vein ending before the tip of the wing ; cross- veins present. 

 26. 



26. Anal cell, when present, short, closed some distance 

 from the hind border of the wing, sometimes absent 27. 



Anal cell elongate, acute, either open or closed toward 

 or near the border of the wing. Second basal cell as a 

 rule separated by a cross-vein from a complete discal 

 cell 29. 



234 



