32 PROCEEDINGS OF THE NATIONAL MUSEUM vol.71 



Legs: Black; femora, tibiae, and tarsi whitish sericeous, at least 

 in fresh specimens; spines black; stout; claws and outer tarsal seg- 

 ments tending toward ferruginous; tarsal spines all stout, those of 

 the fore legs long and often holding their basal diameter well out 

 toward the tip; pulvilli well developed. 



Male. — Hairs usually black on the head; white, black, or brown, 

 tipped with white, or mixed, elsewhere. White hairs appear first 

 near the hinder end of the thoracic mass and extend forward, first 

 along the sides, later dorsally, until they may cover the entire thorax 

 and even influence those on the head. The first step in the change 

 of color appears to be that the tip becomes white while the basal 

 half remains dark. Clypeal hairs sometimes white. 



Head: Clypeus and frons (well up at the sides) silvery pubescent; 

 anterior margin of clypeus considerably below the bottom of the eyes; 

 its margin transverse (sometimes a little rounded), often with a very 

 slight, median emargination ; second filament segment of antenna 

 averaging more than three-fourths the length of the first, but quite 

 variable; mandibles black, sometimes faintly tinged with ferruginous 

 in the middle. 



Thorax: Scutellum faintly, longitudinally rugose behind;' propo- 

 deal disk dull black; closely punctured; with more or less evident 

 transverse rugosities behind. 



Abdomen: Petiole from slightly shorter to slightly longer than 

 hind coxa and trochanter together; part of the first abdominal dorsal 

 plate and of the petiolar expansion beneath it, with the second seg- 

 ment at least, usually ferruginous, but this may increase to include 

 nearly all of the first dorsal plate and the petiolar expansion in front, 

 and as far backward, in extreme cases, as to affect the seventh seg- 

 ment somewhat (in cases of backward extension of the ferruginous, 

 parts of segments involved may show streaks, spots, or shades of dark; 

 the ventral plate or the sides may be partly or entirely ferruginous, 

 while the dorsal middle is black or dark, or vice versa) ; terminal ven- 

 tral plate rounded at the sides, truncate at the end, with a sHght, 

 broad emargination. 



Wings: Generally less deeply fuliginous than in the female; veins 

 dark. In specimens from arid regions these may be lighter, even 

 almost honey-yellow. 



Legs: Tibiae and tarsi whitish sericeous; outer tarsal segments 

 tending, sometimes quite strongly, toward ferruginous. 



Length. — Females, 12-21 mm.; males, 10.5-20 mm. Five hundred 

 and fifty nine examples studied; many others examined less care- 

 fully. The males appear to be far more abundant than the females, 

 'the division in this number being: Males, 397; females, 162. This 

 may, of itself, have some bearing on the possibility that luctuosa is a 

 female form of this species. 



