495 



brownish, with sHght whitish pruinescence. Abdomen brownish 

 black, hypopygiuni shghtly paler. Legs pale brown, tibisc and bases of 

 tarsi paler. Wings clear, cross vein unclouded, veins pale brown. 

 Halteres yellowish brown. 



Pronotum tapering rapidly towards upper margin, discontinued 

 before upper extremity of mesonotum. Hypopygium somewhat like 

 that of viridivcntris, differing in the structure of the superior and in- 

 ferior processes (PI. XL, Fig. 8), in the much shorter auxiliary proc- 

 ess which does not reach beyond the apex of the inferior process, and 

 in the shape of the extension of the dorsal plate, which tapers more 

 gradually and has a single transverse series of hairs near base of con- 

 stricted portion. Fore tarsi without long hairs; basal joint one fifth 

 longer than fore tibiae (42: 35) ; mid and hind legs with long pale 

 hairs. Third vein ending just beyond beginning of apical curve of 

 wing; cross vein at middle of wing. 



Female. — Differs from the male in having the ground color of 

 thorax yellowish and the apices of the abdominal segments narrowly 

 pale . 



The basal joint of fore tarsi is one tenth longer than the fore tibia 

 (33:30). 



Length, 3 mm. 



Type locality, Madison, Wis., May i, 19 10 (J. G. Sanders). 



14. Tanytarsus exiguus Johannsen 



Tanijtarsus exiguus Johannsen, Bull. 86, N. Y. State Mus., 1905, p. 294. 



Larva. — Length, 3-4 mm. Greenish, or yellowish, head brown. 

 Case with three filaments projecting at apex. Antennae more than one 

 and a half times as long as mandible, apical process of basal joint 

 longer than second joint; labial plate somewhat similar to that shown 

 in Figure 19, Plate XXIX, the central tooth with more distinct shoul- 

 ders forming weak subapical teeth, the first lateral tooth also with 

 shoulder on outer side ; mandible with three distinct teeth on ventro- 

 lateral margin. 



Pupa. — Length, 2-3 mm. Yellow. Thoracic respiratory organs 

 slender, simple, pointed apically, without distinguishable surface 

 hairs ; second abdominal segment with apical transverse series of black 

 setulce, and two large subtriangular patches of very weak setulae on 

 dorsum; third segment with two small rounded patches of conspicuous 

 black setulae near apex, the dorsum posterior to these being covered 

 with weak setulae ; fourth segment with a conspicuous group of black 

 setulae near base of median line and two weaker elongate submedian 



