296 Hominoxious Arthropods 



h. Arista terminal; hind metatarsus enlarged, sometimes orna- 

 mented, hind tarsus more or less flattened beneath 



PLATYPEZIDiE 



hh. Flies having a different combination of characters. 



i. Head large, eyes occupying nearly the entire head; cell 

 R4+5 narrowed in the margin; small flies . .Pipunculid^ 

 ii. Head and eyes not unusually large. 



]. Squamffi (tegulas, or calyptras, or alulae) not large, eften- 

 quite small, the lower one lacking, or at most barely 

 projecting from below the upper one (antisquama) ; 

 front of both male and female broad, the eyes therefore 

 widely separated; posthumeral and intraalar macro- 

 chaeta not simultaneously present; thorax usually 

 without a complete transverse suture; postalar callus 

 usually absent; the connectiva adjoining the ventral 

 sclerites always visible; hypopleural macrochstae 

 absent; last section of R4+5 and M1-1-2 with but few 

 exceptions nearly parallel; subcostal vein often wanting 

 or vestigial or closely approximated to Ri; the latter 

 often short, basal cells small, the posterior ones often 

 indistinct or wanting; vibrissae present or absent 



ACALYPTRATE MUSCOIDEA 



k. Subcosta present, distinctly separated from Ri at the 

 tip; Ri usually ends distad of the middle of the 

 wing; the small basal cells of the wing distinct. 



I. A bristle (vibrissa) on each side of the face near the 



margin of the mouth. Cordylurid^, Sepsid^, 

 Phycodromid^, Heteroneurid^, Helomyzid^. 



II. No vibrissas present. 



m. Head nearly spherical, cheeks broad and re- 

 treating; proboscis short; the cell R5 closed or 

 narrowed in the margin; legs very long; tarsi 

 shorter than the tibiae. Calobata and other 



genera MlCROPEZlD^ 



mm. FHes with another combination of characters. 



Rhopalomerid^, Trypetid^, Ortalid^, 



sciomyzid^. 



kk. Subcosta absent or vestigial, or if present, then 



apparently ending in the costa at the point where 



Ri joins it ; Ri usually ends in the costa at or before 



the middle of the wing. 



I. Arista long plumose, or pectinate above; oral vibris- 



sas present; anal cell complete; costa broken at 

 the apex of Ri. Drosophila, Phortica, and other 

 genera DROSOPHILIDiE 



II. With another combination of characters. 



m. The cell M and first M2 not separated by a cross- 

 vein; anal cell absent; front bare or only 



