NO. I BLACK FLIES OF GUATEMALA — DALMAT 197 



margin, to the presciitellar depression, the latter also being completely 

 white-pruinose ; very narrow stripe of white pruinosity on midline ; 

 wide band of white pruinosity around entire periphery ; short, yellow, 

 scalelike hairs, not in packets, sparsely distributed on anterior fourth 

 of mesonotum ; short black hairs also distributed over mesonotum, 

 longer ones present on prescutellar region. Humeral angles shiny 

 brown, with yellow, scalelike hairs. Scutellum brown, with 3-4 short 

 black hairs on each side. Postnotum brown, white-pruinose, devoid 

 of hairs. Pleura brown, evenly white-pruinose. Stem of halter dull 

 brown, the knob tan, cup-shaped. Wings, 4.1 mm. long and 1.7 mm. 

 wide ; relation of length of body to wing, i : i ; Sc with basal three- 

 fourths pilose; Ri with its apical three-fifths both pilose and spiny; 

 R2+3 pilose except for very small basal section at the base of which 

 are 2 hairs ; Cu2 arcuate ; discal cell absent. 



Legs : Leg i, length, 4.3 mm. ; coxa, trochanter, and femur light 

 brown ; tibia brown on basal fourth, dark brown on apical fourth, and 

 yellow in midregion ; tarsus dark brown. Leg 2, length 3.8 mm. ; 

 coxa dark brown, with posterior edge black ; trochanter light brown ; 

 femur light brown, with wide dark-brown apical ring; tibia divided 

 into the following color bands from its base to apex: light brown, 

 dark brown, yellow, dark brown ; basal three-fourths of basitarsus and 

 basal fourth of second tarsal segment light brown, the remainder of 

 these segments, as well as all of segments 3-5, black. Leg 3, length, 

 4.5 mm. ; coxa dark brown ; trochanter light brown ; femur and tibia 

 as on leg 2 ; basal half of basitarsus and second tarsal joint light brown, 

 the remainder of these segments, as well as all of segments 3-5, dark 

 brown to black ; relation of basitarsus to second segment, 4:1; cal- 

 cipala well developed, but not quite reaching the pedisulcus ; pedisulcus 

 very well developed on basal third of second segment, almost cutting 

 through entire width of segment ; claw with well-developed heel and 

 with strong, long, sharply pointed subbasal spur (pi. 35, fig. 242). 



Abdomen : Anterior half of tergite of segment i black, the posterior 

 half tan ; pleurites black, with long tan hairs reaching the third seg- 

 ment. Segment 2 light brown, its posterior half white-pruinose; 

 pleurites brown. All other segments with tergites black and pleurites 

 brown, the latter with short tan hairs. Sternites tan, with dark band 

 in central region. 



Genitalia: Cercus (pi. 31, fig. 184) somewhat trapezoidal in 

 shape, dorsal margin sinuous, higher than long (wide), clothed with 

 long, strong hairs and numerous fine spicules. Anal lobe (pi. 31, 

 fig. 184) narrow where it curves around the cercus, with extensive 

 expanded region ventral to the latter ; with similar investiture to that 



