The True Flies 



Lower calypter minute or wanting, eyes broadly separated 

 in both sexes (Group Acalypterce) 40 



Group CALYPTERATVB Desv. 



35 — Oral opening large, the proboscis well developed 36 



Oral opening very small, the proboscis and palpi rudimentary, 

 the antennae very short and somewhat concealed in 

 cavities; rather large, robust flies Family CEstridce. 



36 — Pleura bearing a perpendicular row of bristles above the pos- 

 terior coxae 37 



Pleura not bearing such a row of bristles, those of the abdo- 

 men weak 39 



37— Antennal arista hairy or plumose, at least on the basal 

 portion 38 



Antennal arista bare or pubescent Family Tachinidce. 



38 — Arista of antennae hairy nearly or quite to the apex, legs 

 usually very long, abdomen provided with stout bristles 

 Family Dexiidce. 



Arista bare on its broad apical portion or the bristles of the 



abdomen weak, legs short and robust 



Family Sarcophagidce. 



39 — Fourth vein before its apex strongly curving toward the third 

 * . . Family Muscidce. 



Fourth vein not or only slightly curving toward the third . . . 

 Family Anthomyiidce. 



Group ACALYPTERCE Macq. 



40 — Auxiliary vein distinct, separated from the first and terminat- 

 ing in the costa, the anal cell present 41 



Auxiliary vein absent, or confused with the first vein — 52 



41 — Anterior oral margin bearing a distinct bristle on either side 42 



Anterior oral margin never bearing such bristles, their places 

 sometimes occupied by several short bristly hairs — 45 



42 — Costa of the wings bearing numerous spines, or the bristles 

 of the front confined to the upper half 44 



Costa of the wings not beset with spines, front usually bristly 

 from the vertex almost to the antennae 43 



90 



