INSEICUTOR INSClTly© MENSTRUUS 89 



the palpi, labella and base of antennae to arista yellow, knees 

 and tibiae yellowish, the anterior tibiae less so. Front at nar- 

 rowest averaging 0.12 of entire headwidth (five specimens gave 

 0.11, 0.12, 0.12, 0.12, 0.13); third antennal joint a little bul- 

 bous at tip; parafacials about as wide as third antennal joint; 

 bucca about 0.3 the eyeheight; arista very slightly pubescent. 

 Thorax cinereous with changing reflections dorsally; sterno- 

 pleurals two strong, no trace of a third ; pleurae with only pale 

 pile, the bristles, however, black. Abdomen shining black in 

 most lights on half or more of each segment, the base and in 

 certain lights nearly all the tergite, however, silvery pollinose. 

 First segment with a marginal pair, second with marginal and 

 discal pairs, third with discal pair and marginal row of 8; 

 fourth with discal and marginal rows. First genital segment 

 retracted, hardly visible; second large, black, apically more 

 reddish, nearly bare. Inner forceps minute, united, the base 

 heart-shaped, with long hairs directed backward, and with a 

 slender, drawn-out tip ; outer forceps about twice as long, 

 brown, wide at base, tapering to a slender beak-like point that 

 is curved slightly forward, densely hairy on outer side to be- 

 yond middle ; penis shining brown, very thin in profile, just 

 before its apex giving off in front at right angles a long flat 

 process which curves gently upward and is divided at tip. 

 Gaspers not visible in the prepared specimen. Fifth sternite 

 deeply incised, forming two convex lobes, rather prominent, 

 black. Legs black, tibiae yellowish ; front tibiae with an anterior 

 row of about six even and rather long spines, and with two 

 on outer hind side ; middle tibiae on outer front side with 

 three, the middle largest and lower smallest, also one large 

 inner and three on outer hind side ; hind tibiae with a very 

 uneven row on outer hind side, three on inner hind (the inter- 

 mediate minute), and two on outer front. Claws and pulvilli 

 all very long. Wings hyaline, third vein with about three hairs 

 at base ; fourth vein bent almost at a right angle, occasionally 

 a little angulated. 



Female. Smaller; front uniformly narrowed to extreme 

 vertex, where it is about one-sixth headwidth ; only five pairs 



