6 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.73 



26. Male with bright silvery parafrontals ; antennae black, third joint in male 



three times the second; facial ridges of male strongly bristly (eastern 



United States) argentifrons, new species. 



Male with parafrontals generally with yellowish pollen, dull ; antennae some- 

 what reddish, third joint in male twice the second ; bristles of facial 

 ridges not uncommonly strong (United States) townsendi, new species. 



27. Third antennal joint only a little longer than second ; vibrissae more than 



two-thirds the length of the third antennal joint above oral margin (wide- 

 spread) bicincta Robineau-Desvoidy. 



Third joint usually more than twice the second, vibrissae never more than 

 half the length of the third joint above the oral margin 28. 



28. With only a single row of frontal bristles, not counting the orbitals in 



female 29. 



With at least a partial second row of frontals 30. 



29. Third abdominal segment with only narrow trace of poilinose basal band, 



male with bright silvery parafrontals (Brazil) potens Wiedemann. 



Third abdominal segment with pale yellow basal crossband covering half of 

 the segment (Salvador) nigrifrons, new species. 



30. Second abdominal segment with two or three pairs of median marginals; 



robust, spiny species (Guatemala, Brazil) lata, new species. 



Second abdominal segment with only one pair of median marginals as 

 usual 31. 



31. Third abdominal segment with only a very narrow basal poilinose band, 



covering about one-sixth of its width (Brazil) smithi, new species. 



Third abdominal segment with interrupted band covering about one-half of 

 its width, rarely a little less 32. 



32. Hind coxae on inner side with two or three strikingly long, stout spines 



directed backward (Paraguay, Brazil, Cuba) spinicoxa, new species. 



Hind coxae with distinct but not striking bristles 33. 



33. Hind tibia stout, with coarse, irregular bristles on outer side (Brazil). 



esuriens Fabricius. 

 Hind tibia with a dense row of almost even cilia on outer side 34. 



34. Second abdominal segment shining black, parafrontals in male dark plumbe- 



ous (Brazil, British Guiana) williamsi, new species. 



Second abdominal segment opaque black, parafrontals in male with dense 

 yellowish pollen (Canal Zone, Brazil) canalis, new species. 



BELVOSIA WEYENBERGHIANA Van der Wnip 



Belvosia weyenberghiana Van der Wulp, Tijdsch. v. Ent., vol. 26, 1883, 

 p. 26. pi. 1, fig. 16. 



Male. — Front at vertex 0.34 of the head width, the sides nearly 

 parallel for a short distance ; face, parafacials, cheeks, and posterior 

 orbits white poilinose. Parafrontals with much thinner pollen, dark 

 and subshining over most of their area. Frontal bristles very irreg- 

 ular, hardly in three rows, more erect than in most of the species. 

 The hairs of the upper parafacials are black ; cheek nearly two- 

 thirds the eye height, with black hairs, some quite bristly. Anten- 

 nae blackish, the third joint quite short, one and a half times the 

 second. Vibrissae about the length of the second antennal joint, 

 above the oral margin; facial ridges with black bristles extending 

 above the middle. Palpi yellow. 



