50 Families and Genera of 



22. Hind femora slender; abdomen elonjjate, usually slender toward 



the base ; front of female long, narrowed above. Baccha 

 Hind femora thickened 23 



23. Epistoma produced anteriorly, in profile deeply concave from 



antennas to oral margin ; third joint of antennte rounded. 



Sl'HEGINA 



Epistoma produced more downward, in profile gently concave ; 

 third joint of antennaj not rounded. . . . Neoascia 



24. Abdomen witli definite yellow cross-bands, interrupted or en- 



tire. 25 



Abdomen not with definite yellow cross-bands. . . .32 



25. Hind femora extraordinarily thickened. . . . Stritta 

 Hind femora slender ■ . . 2(i 



26. Sixth abdominal segment in the male as long as the two prece- 



ding together, cylindrical; fifth segment in the female one- 

 half as long as the preceding Eupeodes 



Sixth segment not peculiar ; the fifth segment in the female one- 

 third or one-fourth as long as the preceding. . . 27 



27. Front very convex ; eyes of male with an area of enlarged facets 



above Catabomba 



Front not remarkablj- convex. 28 



28. Thinl longitudinal vein with a distinct curvature into the first 



jjosterior cell ; third joint of antennee elongate oval. IDidea 



Third longitudinal vein straight or gently curved ; epistoma not 



produced (if produced in a long porrected snout, Rhingia. ) 



Sykphis 



29. Dorsum of thorax with a median cinereous line. Mesograpta 

 Dorsum without such line. ...... 30 



30. Eyes of male with an area of enlarged facets above ; fourth seg- 



ment of abdomen with two median yellow- stripes and an ob- 

 lique side spot Allograpta 



Eyes of male not with an area of enlarged facets above ; fourth 

 abdominal segment not so marked. . ... 31 



31. Face projecting below ; slender species. . Sph.kropiioria 

 Face receding; abdomen oval, at least not slender. 



Xanthogramma 



32. Abdomen oval, black, basal portion light-colored ; thickly pilose 



species. Leucozona 



Thinly pilose species, not so marked. .... 33 



