40 PROCEEDINGS OP THE NATIONAL MUSEUM vol.83 



Male.— Front 0.252 of the head width (average of five: 0.26; 0.25; 

 0.25; 0.25; 0.25), hardly widening to middle, thence rapidly so down- 

 ward ; paraf rontals thinly gray pollinose often blackish before vertex, 

 clothed with sparse short hairs; median stripe reddish brown, hardly 

 narrowed behind and extending on each side of triangle to vertex; 

 inner verticals moderately strong, directed posteriorly, outer pair 

 vestigial; ocellar bristles small, proclinate, divergent; orbitals absent; 

 frontal bristles about five in each row, descending to level with apex 

 of second antennal segment, uppermost pair reclinate, the others 

 directed inward; face rather long and receding, deeply excavated, 

 ground color black, gray pollinose, its ridges bare except a few 

 bristly hairs above vibrissae; parafacial covered with shining gray 

 or almost silvery pollen, bearing a row of bristles along the inner 

 margin which become longer and stouter downward; vibrissae sit- 

 uated on level with front edge of mouth; antennae as long as face; 

 third segment black, with the anterior edge practically straight, 

 about seven times the length of second; basal segments tinged with 

 red, the first longer than second and extending well above the level 

 of the front; arista slightly shorter than third antennal segment, 

 black, thickened on proximal two-fifths, basal segments short but 

 distinct; cheek about two-fifths the eye height; proboscis short, 

 labella fleshy ; palpi slender, hardly thickened apically, yellow ; eyes 

 distinctly hairy; beard white. 



Thorax black, thinly dusted with gray pollen ; mesonotum sub- 

 shining, the vittae poorly defined; chaetotaxy as in validinervis^ 

 except that there are usually three pairs of acrostichals before the 

 suture; scutellum black, subshining; infrasquamal hairs present; 

 postscutellum normally developed; calypters white. 



Abdomen shining black, with narrow silvery basal bands on inter- 

 mediate segments, the fourth faintly pruinose at most; first segment 

 without median marginals; second with a single pair; third and 

 fourth with marginal rows, the latter also with discals at the sides 

 but none on the middle above; genital segments black; inner forceps 

 united, flat behind, tapering from base to an acute ti]5 ; outer forceps 

 yellowish, shorter than inner pair, tapering outward, the tips rather 

 narrow and darker. 



Legs black; claws and pulvilli elongate; wings subhyaline; veins 

 bare except third, which is setulose almost to small cross vein; last 

 section of fifth vein at most one-third the length of preceding sec- 

 tion; apical cell closed, Avith petiole longer than small cross vein; 

 costal spine small. 



Female. — Front at vertex 0.252 of the head width (average of 

 five: 0.25; 0.25; 0.2C; 0.25; 0.25), widening gradually to base of 

 antennae; parafrontals blackish, subshining; orbitals two pairs, pro- 



