NORTH AMERICAN DIPTERA. 17o 



Venter destitute of a cross-band of black tonientuni on base of third seg- 

 ment, but with such a cross-band at l)ases of fifth and sixth segments: 

 base of wings in the male furnished with an epaulette of silvery scales: 



the last abdominal segment destitute of such scales 11. niolitor. 



27.— Proboscis not or scarcely i)rojecting beyond the oral margin 28- 



Proboscis projecting from one-fourth to one-half its length beyojid the oral 

 margin; front tibiae provided witli bristles: antennae wholly black; 



face black, retreating below 18. caprea. 



28.— Scutellum wholly black 29. 



Scutellum partly, or wholly reddish ; front tibiic destitute of bristles; legs 



and first two antennal joints reddish 34. aduiiibrata. 



29.— Abdomen furnished with black tomentum 30. 



Abdomen destitute of black tomentum 33. 



30.— Segments four and five of abdomen provided \j'ith white or yellow tomen- 

 tum '■^^• 



Segments four and five destitute of white or yellow tomentum ; black to- 

 mentum of body api)earing brassy in certain lights 63. tellliris. 



31.— Posterior femora and tibiae destitute of a fringe of long scales; outline of 



brown on wings indistinct 32. 



Posterior femora and tibiffi furnished with a dense fringe of long .scales, 

 both above and below ; outline of brown on wings well defined. 



16. inops. 

 32.— Brown of wings invades the discal and the third and fourth posterior cells. 



27. vaiia. 



Brown of wings does not invade these cells 74. rauiiiis. 



33.— Pile of breast wholly white or yellowish, never largely black 34. 



Pile of breast largely or wholly black 14. anna. 



34. — Face reddish; front tibiae provided with bristles; claws of front tarsi well 



developed 33. odififia. 



Face largely or wholly black; front tibiae destitute of bristles; claws of 



front tarsi minute IT- eudora. 



35.— Scutellum wholly black "'6. 



Scutellum partly or wholly reddish 74. 



36. — Abdomen destitute of black tomentum -u. 



Abdomen provided with black tomentum M. 



37. — Face, femora and tibiae partly or wholly reddish ■18. 



Face wholly black 19. 



38. — Apex of wings beyond base of second sul)n)arginal cell distinctly hyaline 



and brown '"9. 



Apex of wings beyond base of second snbmarginal cell wholly hyaline. 



never distinctly hyaline and brown 41. 



39.— Proboscis not projecting beyond the oral margin ; front tibiae destitute of 



bristles JO. 



Proboscis projecting half its length beyond the oral margin; front tiliia; 



provided with bristles 3. C'lolia. 



40.— Brown of wings fills apex of first posterior cell ; a brown spot in apex of 



anal cell 2. serpentina. 



Brown of wings does not fill apex of first [josterior cell ; no brown spot in 

 apex of anal cell 45. niira. 



TRANS. AM. ENT. SOC. XIX. JCLY, 1>S92. 



