NO. I BLACK FLIES OF GUATEMALA DALMAT II9 



half of the postnotum. Pleura dark brown, with gray pruinosity ; all 

 tufts yellow, the pre-alar group more bronze. Stem of halter with 

 sten. brown at base, lighter at apex, the knob creamy yellow. Wings, 

 3.3 mm. long and 1.4 mm. wide; relation of body length to wing, 

 1:1.2; Sc pilose along basal two-thirds; Ri completely pilose, the 

 distal two-ftfths with spines as well ; R2+3 pilose except along an ex- 

 tremely short basal section ; Cua arcuate ; discal cell absent. 



Legs: Leg i, length, 2.7 mm., coxa and trochanter light brown; 

 femur light brown with apical dark ring ; tibia light brown, the base 

 and apex with dark rings, the basal one lighter than the apical ; tarsus 

 black. Leg 2, length, 2.5 mm.; coxa dark brown; trochanter light 

 brown ; femur and tibia as on leg i ; tarsus black, the basitarsus and 

 segments 2 and 3 with apical spurs. Leg 3, length, 3.1 mm.; coxa 

 dark brown ; trochanter light brown ; femur and tibia as on legs i and 

 2 ; basitarsus light brown on basal two-thirds with very small basal 

 black band, the apical third black ; segments 2-5 black ; segments 2 

 and 3 with apical spur; relation of basitarsus to second segment, 

 4.6 : 1 ; calcipala well developed, reaching the pedisulcus ; pedisulcus 

 well formed one-third the distance from the base of second segment ; 

 basal heel of claw well developed, claw with secondary, spear-shaped 

 structure arising near the base (pi. 35, fig. 268). 



Abdomen: Tergite of segment i light brown with rather long 

 yellow hairs; pleurites brown, with fringe of very long pale-yellow 

 hairs. Segment 2 with tergum brown, the pleura black, all with rather 

 long yellow to bronze scalelike hairs. Other segments black, with 

 dark-brown tergites, all densely covered with yellow scalelike hairs ; 

 some of these scalelike hairs appear almost silvery ; hairs on segments 

 7 and 8 shorter than on other segments ; plates of tergites 3-7 narrow. 

 Sternites brown, with tan hairs. 



Genitalia : Cercus (pi. 29, fig. 136) almost oval in shape, posterior 

 margin slightly concave, its height more than twice its length (width). 

 Anal lobe (pi. 29, fig. 136) smaller and narrower than the cercus, its 

 anterior margin convex, posterior margin concave, curved around the 

 cercus ventrally where it ends in blunted point; with long spines on 

 ventral (anterior) margin only. Genital rod (pi. 29, fig. 138) not 

 heavily sclerotized, without basal dilatation ; apical expansions of arms 

 of genital fork triangular in shape, the apical angle, outer basal angle, 

 and the margin between the two well sclerotized ; apical angle rather 

 sharply pointed ; arms of genital fork emerge close to one another, 

 so that their inner margins are almost parallel. Ovipositor (pi. 29, 

 fig- 137) somewhat conical in shape, tapered distally, the apex 

 rounded. 



