110 NORTH AMERICAN DIPTERA. 



TABLE OF GENERA. 



1. Second joint of the antennae with a short spinous bristle at the anterior 



upper end 2 



Second joint of antennae without a spinous bristle at the anterior end. 8 



2. The costal vein reaches to the tip of the third longitudinal vein. 3 

 The costal vein reaches to the tip of the fourth longitudinal vein. 4 



3. Tip of the abdomen in the male with elongated bristles. 



DICH^TA Meigen. 

 Tip of the abdomen in the male without elongated bristles. 



NOTIPHILA Fallen. 



4. Abdomen broad. . ; , . . . DISCOMYZA Meigen. 

 Abdomen not broad 5 



5. Face on the upper part flat or gently convex, not carinate ; third joint 



of the antennae oval PSILOPA Fallen. 



Face distinctly carinated above. . . . . . . . 6 



6. Cheeks narrow ; eyes long. .. . . . CLASIOPA Stenhammer. 



Cheeks broad, eyes round. . 7 



7. Clypeus prominent. . . . . . ARTHYROGLOSSA Loew. 



Clypeus projecting but little beyond the oral margin. 



HECAMEDE Halliday. 



8. Middle tibiae with several long bristles exteriorly. PARAMMNA Loew. 

 Middle tibiae without long bristles exteriorly. .... 9 



9. Oral opening small ; eyes usually pubescent (Ifydrellinte). . . 10 

 Oral opening large (Ephydrince). ....... 16 



10. Front femora thickened. . . 11 



Front femora not thickened. . 12 



11. Front femora much thickened; first posterior cell narrowed at the bor- 



der of the wing. . . . . . . OCTHKRA Latreille. 



Front femora moderately thickened ; third and fourth veins parallel 

 (West Indies). . . . v . . OCHTHEROIDEA Williston. 



12. Eyes thickly but short pubescent. . . HYDRELLIA Desvoidy. 

 Eyes sparsely pubescent or bare 13 



13. Sides of the face wholly without bristles. . HYADINA Halliday. 

 Sides of the face with bristles. ....... 14 



14. Eyes wholly bare. . . ' f .15 



Eyes sparsely pubescent; clypeus hidden. PIIILHYGRIA Stenhammer. 



15. Clypeus projecting; anterior part of mesonotum without bristles. 



PELINA Halliday. 

 Clypeus hidden ; anterior part of the mesonotum with bristles. 



PELOMYIA Williston. 



