NO. I BLACK FLIES OF GUATEMALA — DALMAT 265 



on anterior margin lateral to midline from which arises a longitudinal 

 stripe of white pruinosity that joins posteriorly with the white prui- 

 nosity of the prescutellar region ; lateral margins also white-pruinose ; 

 short, narrow, yellow, scalelike hairs sparsely distributed over entire 

 mesonotum ; many long black hairs in prescutellar region. Humeral 

 angles black, with white pruinosity. Scutellum dark brown, shiny, 

 with short, yellow, scalelike hairs and long black ones. Postnotum 

 velvety black, white-pruinose, devoid of hairs. Pleura black with white 

 pruinosity. Stem of halter dark brown at the base, tan toward the 

 apex, the knob yellow. Wings, 3.4 mm. long and 1.4 mm. wide; rela- 

 tion of length of body to wing, i : i .3 ; Sc pilose except for very small 

 apical region ; Ri pilose and spiny along distal three-fifths ; R2+3 pilose 

 except for very short basal section ; Cua arcuate ; discal cell absent. 



Legs: Leg i, length, 3.1 mm.; coxa black; trochanter and femur 

 dark brown; tibia yellow on basal three-fourths, black on apical 

 fourth ; tarsus black. Leg 2, length, 2.8 mm. ; coxa and trochanter 

 black ; femur black with small basal brown area ; tibia and basitarsus 

 yellow on basal half, black on apical half ; tarsal segments 2-5 black. 

 Leg 3, length, 3.6 mm. ; coxa black ; trochanter brown ; femur black ; 

 tibia brown on basal third, black on apical two-thirds; basal half 

 of basitarsus and of second segment yellow, the remainder of these 

 segments, as well as all of segments 3-5, black ; relation of basitarsus 

 to second segment, 4.4 : i ; calcipala very well developed, passing the 

 pedisulcus ; pedisulcus very well developed on basal fourth of second 

 segment; claw with well-defined heel and with secondary submedian 

 tooth (pi. 35, fig. 256). 



Abdomen : Tergite and pleurites of segment i black, with white 

 pruinosity, the pleurites with long dark hairs that reach the third seg- 

 ment. Segment 2 black with white pruinosity. Other segments bluish 

 black, shiny, the pleura with brown hairs; last two segments with 

 long black hairs. Sternites tan. 



Genitalia: Cercus (pi. 34, fig. 229) almost rectangular in shape, 

 its height twice the length (width), clothed with some long, strong 

 hairs and with numerous minute spinelike hairs. Anal lobe (pi. 34, 

 fig. 229) large, very high, curving somewhat around the cercus, espe- 

 cially at the ventral margin; posterior ventral angle of anal lobe 

 pointed. Genital rod (pi. 34, fig. 231) with triangular-shaped basal 

 dilatation ; apical expansions of genital fork triangular in shape, all the 

 angles blunt ; only outer basal angle pigmented. Ovipositor (pi. 34, 

 fig. 230) triangular in shape, its height about equal to the base. 



Pupa (pi. 38, fig. 313, and pi. 39, fig. 353). — Granulosity on entire 

 thorax, not very pronounced ; 5 stout, simple, spinelike trichomes on 



