38 PROCEEDIISrGS OF THE NATIONAL MUSEUM vol.75 



16. Middle femora of normal form, not emarginate 17. 



Middle femora more or less strongly emargiuate posteriorly 19. 



17. Scutum with a pair of discal marks esigua. 



Scutum without discal marks 18. 



18. Clypeus with black more or less extensive on dorsal border puUa. 



Clypeus wholly pale and silvery argentata. 



19. Scape black above; mesosternum marked with black; genital stipes as in 



Figure 33 femorata. 



Scape entirely yellow; mesosternum yellow; genital stipes as in Fig- 

 ure 34 divergens. 



20. Pulvilli distinct 21. 



Pulvilli indistinct 35. 



21. Scutum without discal markings 22. 



Scutum with discal marks more or less well developed 2-5. 



22. Head narrower than thorax; width of second cubital cell on radial vein 



about half its width on cubital emarginata. 



Head normal, wide as thorax ; second cubital cell normal 23. 



23. Anterior and middle femora entirely yellow argentata. 



Anterior or middle femora or both marked with black 24. 



24. Spots on scutellum rectangular ; spots on either side of anterior ocellus. 



pulla. 

 Spots on scutellum triangular ; V-shaped spot enclosing anterior ocellus. 



megacera, 



25. Di.-cal marks on scutum, consisting of a pair of irregular spots, or of pair 



of lines not broken, not curved inward or approximated posteriorly __26. 



Discal marks on scutum in form of a U, either broken, interrupted medially, 

 or broken into lines and spots 28. 



26. Scutellum with pair of large triangular lateral spots pulla. 



Scutellum with a continuous fascia, rarely interrupted on the mediau 



line 27. 



27. Fasciae on tergites yellov? ; that on first tergite deeply emarginate on an- 



terior border at midline or entirely cut through, leaving a posterior me- 

 dian discal spot , pictifrons. 



Fasciae on tergites pale; that on first tergite not deeply emarginate on 

 anterior border argentata. 



28. Second sternite more or less black; not entirely yellow 29. 



Second sternite entirely yellow 31. 



29 Species small, 10-12 mm.; discal marks on scutum narrow and broken: 

 fasciae on tergites rather narrow, wavy, scarcely to be considered emar- 

 ginate , femorata. 



Species larger, 16-20 mm. ; discal marks on scutum two broad lines curved 

 and approximated posteriorly; fasciae on tergites broad and emarginated 

 anteriorly 30. 



30. Tergites without posterior black border; posterior tarsi, save basal joint, 



dusky above speciosa. 



Tergites with a posterior black border; posterior tarsi yellov,' formosa. 



31. Species large, 15-20 mm 32. 



Species small, 10 mm 84. 



32. Clypeus with pair of basal black spots 'oif areata. 



Clypeus entirely yellow 33. 



33. Scape yellow; black spot on mesosternum near middle coxa tenuicornis. 



