362 THE INSECTS 



6. Stigmal plates on black tubercles; lateral fusiform areas distinct. Ortalidae 

 Stigmal plates barely if at all elevated; lateral fusiform areas 



indistinct; stigmal plates often contiguous or nearly so; 



slits long and subparallel Trypetidae. 



7. Slits in stigmal plates rather short, and arranged radiately. ... 8 

 Slits slender and subparallel to each other 9 



8. Two tubercles above anal area; stigmal field with distinct 



processes around it Anthomyiidae. 



Four or more tubercles above anal area; slits of stigmal plates 



usually pointed at one end Muscina. 



9. A button to each stigmal plate; slits rather transverse to body. . . Calliphorinae. 

 No button to stigmal plates, slits of one plate subparallel to 



those in opposite plate; plates at bottom of a pit Sarcophagidae 



