TABANID^ OF OHIO. 33 



13. Body altogether black ; femora of all the legs dark brown 



or black plangens. 



Body usually distinctly marked with yellow; femora yellow 



except sometimes at base 14. 



14. Face black with a median stripe of yellow pollen frigidus. 

 Face yellowish in the middle 15. 



15. Apical-spot large, reaching beyond the second submarginal 



cell, and invading the first posterior 16. 



Apical-spot does not reach beyond the second submarginal 



cell 18. 



16. The hyaline space between the cross-band and the apical-spot 



is confined to a small triangle in the second and third 

 posterior cells moechns. 



The hyaline triangle reaches across the first posterior cell 17. 



17. Abdomen with a broad yellow longitudinal stripe in the 



middle enclosed between two black stripes univittatus. 



Abdomen uniformly black or black with three dull yellow 

 . . stripes lugens. 



18. Abdomen yellow with four black stripes 19. 

 Abdomen black, yellow on the sides, and with yellow tri- 

 angles on the segments indus. 



19. Frontal callosity and scutellum yellowish vittatus. 

 Frontal callosity black ; scutellum at base more- or less 



blackish striatus. 



Key to the Males. 



1. Apex of the wing beyond the cross-band is hyaline 2. 

 Apical-spot present 4. 



2. Face yellow in the middle niger. 

 Face wholly black 3. 



3. Base of fifth posterior cell with a hyaline spot ; anal cell nearly 



hyaline • carhonariiis. 



Base of the fifth posterior cell uniformly brown; anal cell 



infuscated celer. 



4. Whole body brown 5. 

 Body black or at least plainly marked with black 6. 



5. First segment of antenna swollen ; abdomen uniformly brown 



abpv-e, with a small triangle on each segment behind the 

 first brunneus. 



First segment of antenna not swollen ; abdomen above lighter 

 at base with a darker design on each segment behind 

 the first Aavidus. 



C. Abdomen grayish black, or black with or without a median 



yellow stripe 7. 



Abdomen at least yellow on the sides of the first two seg- 

 ments ; or with a middorsal row of gray triangles 10. 

 7. Abdomen black with a middorsal yellow stripe 8. 

 Abdomen uniformly black 9. 

 8; The hyaline triangle produced forward to the costa obsoletus. 



■ The hyaline triangle not produced beyond the second longi-- 

 ' ' - tudinal vein • lugens. 



9.. Hyaline triangle unusually small, confined to the apices of the 



second and third posterior cells moechus-: 



■'---'. Hyaline triangle not unusually small ; dark picture of the wing 



rather dim - . -. \ ■ > plangens'. 



