130 NORTH AMERICAN DIPTERA. 



Prothoracic and stigmatic bristles usually present; when wanting the 

 thorax nearly bristleless. One to three sternopleural bristles present. 

 Thorax with one to five dorsocentral bristles; the scutelluin with 

 two to four. Wings usually short 3 



2. Head broad; palpi spoon-shaped or leaf-like. . HYDROMYZIN^C. 

 Head round not especially broad ; palpi linear or rarely ribbon-like 



(Scalophagmce). SCATOPHAGA. 



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



NORELLIN.E. 

 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- 



tennas short ; the arista bare or pubescent. . CLEIGASTRIN^E. 



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

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

 usually bristly. ', . . . . . CORDVLURIN^;. 



CORDYLURIN.E. 



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



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



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



ent. .. . 3 



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

 present. . . . . 6 



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



third. t 4 



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

 jecting; arista long, plumose; shining black species. 



PHROSIA R. Desvoidy. 



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



longitudinal vein straight or gently curved. .... 5 



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



S-shaped. ... . . . SCOLIAPIILEPS Becker. 



5. Arista thickened at the base, plumose to its middle; femora and tibiae 



with strong bristles ; thorax with five dorsocentral bristles ; face 

 narrowed at the antennae; usually shining black species. 



CORDYLURA Fallen. 



Arista scarcely thickened at the base, plumose; femora and tibiae slen- 

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

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



PARALLKLOMMA Becker. 



