DIPTERA. 425 



third segment either with or without a style or bristle, but not 

 divided into subsegments. 



C. Antennae consisting apparently of a single globular segment 

 bearing a long bristle ; wings with some stout veins near the 

 costal margin and other weaker ones extending across the 

 wing unconnected by cross-veins (Fig. 581). p. 475.Phorid;e. 

 CC. Flies that do not present the type of venation represented 

 by Figure 581. 



D. Cells V and first V 2 not separated (see Fig. 571 for an ex- 

 ample of this type). 



E. Vein III with a knot-shaped swelling at the point of 

 separation of veins III2 + 3 and III4 + 5; the cross-vein 

 III-V at or near this swelling; no suture immediately 



above the antennae, p. 467 Dolichopodid^e. 



EE. Vein III with or without a swelling at the point of 

 separation of veins III2 + 3 and 1 1 1 4 4- 5 ; the cross-vein 

 III-V more remote from base of wing; a suture immedi- 

 ately above the antennae, p. 479 MusciDiE. 



DD. Cells V and V 2 separate. 

 E. Vein III four-branched. 



F. Venation intricate, due to an unusual anastomosing of 



the veins (Fig. 555). p. 459 Nemistrinid^e. 



FF. Venation not of the type represented by Figure 555. 

 G. Vertex of head distinctly hollowed out between the 

 eyes (Fig. 557); eyes never contiguous, p. 460. 



Asilid^e. 

 GG. Vertex of head not hollowed out between the eyes; 

 eyes often contiguous in males. 



H. Alulets very large, p. 458 Acrocerid^e. 



HH. Alulets small or rudimentary. 



I. Cell V 3 present. 



J. Vein Ills ending before the apex of the wing 



(Fig. 562). p. 462 Apiocerid^e. 



JJ. Vein Ills not ending before the apex of the 

 win<*. 



K. Empodia pulvilliform, i.e., with three mem- 

 branous lobes beneath the tarsal claws (Fig. 



495). p. 456 Leptid^e. 



KK. With only two membranous lobes beneath 

 the tarsal claws, p. 464 Therevid^e. 



II. Cell V 3 obliterated by the coalescence of veins 

 V 3 and VIIi. 



