380 



tinct pair of hairs near apices of papillae and another near the middle; 

 a pair of long hairs above bases of dorsal blood-gills and another on 

 the inner dorsal surface of each of the pseudopods near their bases. 



Pupa. — Length, 6-7 mm. Yellowish to fuscous. Thoracic respir- 

 atory organs rather long and conspicuous, their apical opening large, 

 surfaces with short setulre (PI. XXIV, Fig. 16) ; no noticeable tuber- 

 cles near bases of respiratory organs. Apical abdominal appendage 

 produced into a fine point at tip, the lateral margin ciliated. 



Imago; Male and Female. — Pale ochreous yellow to reddish yel- 

 low, opaque. Mesonotum with the vittse generally indistinct, the 

 whole disc white pollinose, most distinctly so on the vittae when 

 viewed from behind ; thoracic hairs long and pale except on the 

 posterior third of the spaces between the stripes, where they are very 

 long and dark brown; scutellum yellow; postnotum yellow, with a 

 brown tinge. Abdomen yellow, basal half of each segment brown- 

 ish, the dark color usually carried backward at center on each seg- 

 ment ; surface hairs long and pale except a patch on each side of the 

 median line at posterior extremity of each segment in female, where 

 they are dark brown. Legs yellow ; a brown band near the apices of 

 the femora and near to bases of the tibiae ; mid and hind tibiae with a 

 short black comb at apices. Wings wath two brown bands, one over 

 the center of wing and the other on apical third, the latter much inter- 

 rupted before apex and with a number of rounded clear spots in the 

 dark part. Halteres yellow\ 



Antenna of male very similar to that of monilis, the plumes yel- 

 lowish. Mesonotum with very long hairs which cover almost the 

 entire disc and are most conspicuous on posterior third of the spaces 

 between the vittae and in front of wing-base, where they are brown; 

 a group of hairs present on sternopleura above; scutellar hairs long. 

 Hypopygium as in Figure 12, Plate XXVIL Basal joint of fore 

 tarsus about two thirds as long as fore tibia and distinctly longer than 

 the next two joints together; hairs on fore tarsus at least twice as 

 long as diameter of tarsal joints; mid and hind legs, especially the 

 tibiae, long-haired; fourth tarsal joint on all legs longer than fifth. 



Antenna of female slightly shorter than thorax, surface hairs of 

 moderate length, last joint slightly swollen. In other respects much 

 the same as the male, except that the abdomen is shorter and stouter 

 and the wings are comparatively broader, as is always the case in this 

 genus. The legs are similar in proportions to those of the male, but 

 the hairs are considerably shorter. 



Length, 4.5 mm. 



Illinois localities : Illinois River at Morris, from above the dam at 

 Marseilles (pupae) ; creek at Urbana (pupae) ; Algonquin, July 21, 



