354 NORTH AMHRICAN DIPTERA. 



TABLE OF GENERA. 



BY PROF. C. F. ADAMS. 



i. Proboscis elongate; slender, not retractile, usually as long or longer 



than the dorso- ventral diameter of the head. ... 2 



Proboscis shorter than the head, thick and retractile. . . 15 



2. Proboscis slender and rigid, nearly or quite as long as the head and 



thorax together; labella small. ...... 3 



Proboscis as long as or but little longer than the head. . 8 



3. Scutellum and abdomen armed with spines. . Hystrisiphona. 

 Scutellum and abdomen with the usual macrochaetae. . . 4 



4. .Sides of face bare 5 



Sides of face clothed with short bristles. . Prorhynchops. 



5. Palpi very short, thickened at tip; macrocluctae only marginal. 



Prosena. 



Palpi moderately long, not at all or bnt little thickened at tip; 



macrochaetae usually discal and marginal. .... 6 



6. Claws of male extraordinarily long. 1. . Mochlosoma. 

 Claws of both sexes short 7 



7. Facial carina broad, inflated, depressed. . . Myiomima. 

 Facial carina narrow, not inflated, compressed. Prosenoides. 



8. Abdomen densely covered with macrochaetae. ... 9 

 Abdomen with regularly arranged macrochaetae. ... 10 



9. Vibrissa.- inserted some distance above oral margin 1 3, 4l. 



Hystricodexia. 

 Vibrissas inserted on oral margin. . . . Bathydexia. 



10. Eyes descending not more than two-thirds the distance to lateral 



oral margin. . . . ■ . . . . 1 1 



Eyes descending at least three-fourths the distance to lateral 



margin. .......... 14 



11. Fourth vein with a stump at its bend (1,2). . Scotiptera. 

 Fourth vein without stump at its bend. ..... 12 



12. Macrochaetae of abdomen discal and marginal. . . .13 

 Macrochaetae only marginal (12,13). . . Myiocera. 



13. Face quite concave in profile; vibrissas at oral margin. 



Myioscotiptera. 

 Face nearly perpendicular; vibrissas some distance above oral mar- 

 gin (14,15,19) Rhynchodexia 



