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 a 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 III 3 -H and III + S ; the cross-vein 

 1II-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 III + s and III 4 + &; the cross-vein 

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

 ately above the antennae, p. 479 .............. MusciD^E. 



DD. Cells V and V a 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. 



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

 eyes often contiguous in males. 

 H. Alulets very large, p. 458 .......... ACROCERID^. 



HH. Alulets small or rudimentary. 



I. Cell V 3 present. 



J. Vein III. ending before the apex of the wing 

 (Fig. 562). p. 462 ................ APIOCERID^. 



JJ. Vein III. not ending before the apex of the 

 wing. 



K. Empodia pulvilliform, />., with three mem- 

 branous lobes beneath the tarsal claws (Fig. 

 495). p.456 ...................... LEPTID*. 



KK. With only two membranous lobes beneath 

 the tarsal claws, p. 464 ......... THEREVID*. 



II. Cell V, obliterated by the coalescence of veins 

 V, and VIIi. 



