THE CANADIAN ENTOMOLOGIST. 21 



5. Abdominal spots usually connected on the fourth segment of the 



male, and always connected on the fourth and usually on the third 



of the female 6. 



Abdominal spots never connected on the fourth segment of the (^ , 

 and rarely connected in the ^ barbata, Loew. 



6. Fifth segment with a large keystone-shaped xxi'xxVXw^^.vielanostoina, Lw. 

 Fifth segment with a dorsal line and spot at the anterior 



angle /ativc/itris, Lw. 



7. Abdomen : lateral triangular markings on the second and third seg- 



ments, widely connected on the lateral margin. . .Bruiicri, Johns. 



Abdomen : lateral subtria'ngular markings on tlie second and third 



segments not connected at the lateral margins laiice/'S, Lw. 



8. Scutellum normally yellow, or with base narrowly black 9. 



Scutellum black, or with narrow apical margin yellow 12. 



9. Second segment with lateral triangles ; wings infumated 10. 



Second segment with narrow lateral markings ; wings usually 



dark senaria, Lw. 



10. Posterior margin of fourth segment yellow, with median triangular 



projection uniliinbata, Lw. 



Yellow on posterior margin of fourth segment interrupted 11. 



11. Fourth segment with a small dorsal triangle ; vertex of $ 



black noriuiila, Lw. 



Fourth and fifth segments with small dorsal triangles ; vertex of 9 

 usually yellow norma, Wied. 



1 2. Abdomen with yellow markings 13. 



Abdomen wholly black ^ ( $ unknown) Nevadce, Big. 



13. Abdominal markings linear 14. 



Abdominal markings coalesced, forming a triangular yellow spot at the 



anterior corners of the abdomen : 15. 



14. Fifth segment with a dorsal line ; lateral markings on the segments of 



the ? very narrow Meigenii, Wied. 



Fifth segment with a dorsal triangle ; lateral markings on the seg- 

 ments of the ^ $ prominent apicida, Lw. 



15. Pile of the thorax unusually long and dense; abdomen wide, third and 



fourth segments very convex discaiis, Lw. 



Pile on the thorax normal ; abdomen narrow, and third and fourth 

 segments noticeably convex quaternaria, Lw. 



