274 Syrphidae. 



almost straiglit, going in almost full width over the 



side-margin; scutellum partly black-haired 14. nitidicollis. 



— Antennæ more or less darkened above; abdomen 

 marginale, the bands undulated, not reaching the side- 

 margin or only at their upper corners 18. 



18. Scutellum partly black-liaired; vertex in the male about 

 as long as the eye-sulure; hinder eye-margin not broad, 

 with a row of black hairs; frons of female with side 



dust spots 15. nitens. 



— Scutellum (normally) yellow-haired ; vertex in the male 

 large, longer than the eye sulure; hinder eye-margin 

 broad, without black hairs; male genitalia small ; frons 



of female without side dust spots 16. latifasciatus. 



19. Cubital vein somewhat dipped over the first posterior 



cell 19. lapponicus. 



— Cubital vein nol dipped 20. 



20. Scutellum yellow-haired ; abdominal spots extended over 

 the side-margin (in the male often united) ; male geni- 

 talia large 17, corollae. 



— Scutellum partly black-haired; abdominal spots isolated. ... 21. 



21. Thorax mainly æneous; frons of the male not broad 

 and inflated, in the female with the usual transverse 

 depression and with the black middle line from the 

 verlex going generally below the middle; eyes of the 



male without an area of larger facets 18. luniger. 



— Thorax blue, shining; frons of the male broad and 

 somewhat inflated, of the female somewhat arched, 

 without or with a very slight transverse depression, 

 and with the black middle line from vertex short, 

 often vague or almost wanting ; eyes of the male with 



an area of larger facets 20. arcuatus. 



22. Abdominal bands duplicated by a narrow, black line 



near the base 22. halteatus. 



— Abdominal bands not duplicated 23. 



23. Middle bands of abdomen uninlerrupted and not deeply 

 emarginate 24. 



— Middle bands of abdomen separated into spots or very 



deeply emarginate 25. 



24. Third joint of antennæ dark above; frons with a black, 

 semicircular spot; scutellum dark haired 23. cinctellus. 



— Third joint of antennæ yellow; frons yellow, or in the 

 male with a small, transverse, lunulate, black spot; 

 scutellum quite or mainly yellow-haired 24. cinctus. 



25. Anlennæ pale on basal joinls or beneath the base of 



third joint 26. 



— Antennæ all black 29. 



26. Antennæ all or almost all reddish ; scutellum yellow- 

 haired 27. 



— Antennæ more or less dark or blackish, at all events 



above on third joint; scutellum black-haired 28. 



I 



