j 3 6 NORTH AMERICAN DIPTERA. 



22. Sides of face and cheeks wide; front of female narrower than 



either eve; wings without costal spine (21, 22 1 Hammomyia. 



Either the sides of the face or the cheeks narrow; front of female 



often wider than eye; wings usually with costal spine. 23 



23. Legs wholly or partly rufous or yellow 1 27 1 . . Pegomyia. 

 Legs wholly hlack. 24 



24. The anal vein attains the wing margin. . . Chortophila. 

 The anal vein does not reach the wing margin. . . Azelia. 



25. The eyes occupy the upper two-thirds of the sides of the head. 26 

 The eyes do not occupy the upper two-thirds of the- sides of the 



head 1 24 1. Phorbia. 



26. The anal vein reaches the wing margin. . . Prosalpia. 

 The anal vein does not reach the wing margin. . Ccelomyia. 



27. Anterior cross-vein situated before the end of the first vein. 28 

 Anterior cross-vein under or beyond the end of the first vein. 30 



28. Wings without costal spine. ....... 29 



Wings with costal spine 1 30 1 Choristorna. 



29. Squamae small, equal Euryomma. 



Squamae large, the under longer than the upper. Charadrella. 



30. Palpi unusually broad at tip (14, 15) Lispa. 



Palpi not unusually enlarged at tip. ..... 31 



31. Squamae equal (2).* Schcenomyza. 



Squama? unequal, the lower projecting beyond the upper. 32 



32. Head narrow, antennae not elongate; tibia; with verv long bris- 



tles (23 1 Caricea. 



Not having all the above characters. ..... 33 



33. Four post sutural macrocluc-ta.- (25). . . . Tetrachaeta. 

 With less than lour post sutural macrochseta. 34 



34. Five abdominal segments visible (17) . . . Pentacricia. 

 Only four abdominal segments visible. .... 35 



35. Abdomen cylindrical, incrassate posteriorly: hypopygium prom- 



inent (6). (Compare Hoplogaster 26). Phyllcgaster. 



Abdomen not cylindrical or incrassate behind. ... 36 



36. Head much broader than high i20i. . . . Dexiopsis. 

 Head not markedly broader than high. .... 37 



37. Frontal triangle large, with straight sides, the apex blunt, reach- 



ing the base of the antenna.-. .... Limnospila. 



Triangle with concave sides, the apex sharp, seldom reaching the 



base of the antenna.- (3). ..... Coenosia. 



>: Fucellia. The members of this genus, which has been referred to 

 various families of acalyptrates, are tound often in abundance along 

 sea-shores, about decomposing material which has been thrown up by 

 the waves. They are oi moderate size, blackish gray in color, and 

 will be easily recognized in the males by the hind femora having a 

 bunch of bristles near their base, inserted on a short emargination; 

 the face has numerous vibrissa! bristles; the arista is bare, etc. w. 



