130 NORTH AMERICAN DIPTERA. 



Prothoracic and stigmatic bristle^ ueually present; wlien wanting tlie 

 thorax nearly bristleless. One to tliree sternopleural bristles present. 

 Thorax with one to five dorsocentral bristles ; the scutelluni with 

 two to four. Wings usually short. ...... o 



2. Head broad; palpi spoon-shaped or leaf-like. . IIydromvzix.k. 

 Head round not especially liroad ; palpi linear or rarely riblxm-like 



» (Scalophafjmo). ....... Scatophaga. 



3. Front femora on the inner side with a double row of bristles. 



NORELLIN/K. 



Front femora and tibiae at the most with a single row of bristles.- 4 



4. Face short; palpi small, linear, never with long hairs or bristles. An- 



tennae short; the arista bare or pubescent. . CLEiGASTRiNii:. 



Face long; palpi linear, sometimes flattened, with or without long, ter- 

 minal bristles. Antenna; variable ; arista bare or plumose. Species 

 usually bristly. ....... Cokdylurin/k. 



CORDYLURIN.-?!;. 



1. Palpi small, linear. .......... 2 



Palpi long, widened leaf- like. ....... 14 



2. Palpi with a long terminal bristle; a single sterno-jjleural bristle pres- 



ent .... .J 



Palpi without long terminal bristle ; one to three sterno-pleural bristles 

 present 6 



3. Third antennal joint short; second more or less projecting over the 



third. 4 



Third antennal joint long, as long as the face, the second joint not pro- 

 jecting; arista long, plumose; siiining black species. 



Phrosia R. Desvoidy. 



4. Arista plumoso in the middle or pubescent; costa hairy or ciliate; third 



longitudinal vein straight or gently curved 5 



Arista bare; costa but slightly hairy; tiiird longitudinal vein curved 

 S-shaped. ...... Scoliapuleps Becker. 



5. Arista tliickened at the base, plumose to its middle; femora and tibia^ 



with strong bristles; thorax with five dorsocentral bristles; face 

 narrowed at tlie antenna^; usually shining black species. 



Cordylura Fallen. 

 Arista scarcely thickened at the l)iise, plumose; femora and tibia? slen- 

 der and long but little bristly ; one to three dorsocentral bristles 

 present; face and front of equal width; yellow and black species. 



Parallelomma Becker. 



