8 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



cicatrices, the number of segments in the palpi, the form of the eighth 

 sternite of the male, the narrowing of the radial cell, the direction of 

 the submedial cross vein of the hind wing, and the character of the 

 outwardly opening angle formed by the third cubital cross vein and 

 the radial vein; from Microlembex by the character of the ocellar 

 cicatrices, the form of the eighth sternite of the male, and the fact 

 that the apical end of the radial cell in the wing of Microbemexi does 

 not lie on the costal border. 



KEY TO SPECIES. 



Males. 

 1. Middle tibiae not dilated 2. 



1. Middle tibiae dilated 5. 



2. Apical segment of tarsi black nigripes. 



2. Apical segment of tarsi not black 3. 



3. Abdomen almost entirely yellow sulfurea. 



3. Abdomen black and yellow 4. 



4. Length, 14-18 mm.; dorsal abdominal maculations yellow; spot on mesopleura 



large, usually meeting its fellow on the midventral line duplicata. 



4. Length, 18-20 mm.; dorsal abdominal maculations soiled white; spot on mesopleura 



small, never meeting its fellow on midventral line albicantia. 



5. Abdominal maculations white obliqua. 



5. Abdominal maculations yellow tibialis. 



Females. 

 1. Middle tibiae not dilated duplicata. 



1. Middle tibiae dilated 2. 



2. Abdominal maculations white obliqua. 



2. Abdominal maculations yellow tibialis. 



STENIOLIA NIGRIPES, new species. 



Figs. 7, 12, 17, 18, 19. 



Male. — Black: Labrum, mandibles except tips, clypeus, scape 

 and first two flagellar segments below, lower part of frons continuous 

 with the broad anterior orbits, which are narrowed above, triangular 

 spot on either side of anterior ocellus, narrow posterior orbits broad- 

 ened below, posterior border of pronotum and spot on sides of pro- 

 thorax united on tubercles but separated in front of them by a long 

 irregular black spot, spot on tegulae, short lateral line above tegulae 

 and pair of discal spots on scutum, triangular spots on scutellum, 

 metanotum, curved fascia on dorsum of median segment extended 

 onto its posterior surface where there is a narrow medial interruption, 

 lateral angles and sides of median segment, large irregular spot on 

 mesopleurae, metapleurae, longitudinal line on mesosternum united at 

 either end with the large spot on mesopleurae thus enclosing a large 

 black area, broad fasciae on tergites 1-6, first interrupted medially, 

 deeply emarginate anteriorly in the middle and acutely though less 

 deeply emarginate posteriorly on either side of the median line, 



