NO. I BLACK FLIES OF GUATEMALA — DALMAT 24I 



its height; triangle very small. Antenna 510 /x long, ii-seginented, 

 slightly tapering ; segment 3<i + 2, 3<4+S, 3<ii ; scape and pedicel 

 brown, flagellum black. Palpi black. Frons and clypeus black, white- 

 pruinose, irregularly covered with black hairs. Occipital region black, 

 with white pruinosity and long black hairs. Cornuae of buccopharyn- 

 geal apparatus greatly expanded, somewhat bifurcate, not heavily scle- 

 rotized; median space with marked median concavity, hyaline, very 

 slightly serrated. 



Thorax : Mesonotum velvety black ; 2 subquadrangular, white- 

 pruinose patches contiguous with the anterior margin, one on either 

 side of the midline, from each of which extends a white-pruinose longi- 

 tudinal band that unites with the white-pruinose patch in the prescutel- 

 lar region ; wide band of white pruinosity on lateral margins ; broad 

 band of appressed, short, narrow, golden-yellow, scalelike hairs along 

 entire periphery of mesonotum; short black hairs over entire meso- 

 notum, longer in prescutellar region. Humeral angles brown, with 

 white pruinosity. Scutellum black, white-pruinose, with short, golden- 

 yellow, scalelike hairs and several long black hairs. Postnotum black, 

 with 2 triangular gray-pruinose patches contiguous with the anterior 

 margin and meeting at the midline ; devoid of hairs or scales. Pleura 

 black, with white pruinosity. Stem of halter brown to black, the knob 

 yellow. Wings, 3.1 mm. long and 1.4 mm. wide; relation of length of 

 body to wing, i : i.i ; Sc pilose along its basal three-fifths; Ri pilose 

 and spiny along distal half ; R2+3 pilose except for very small basal 

 section ; Cuo arcuate ; discal cell absent. 



Legs: Leg i, length, 2.6 mm.; coxa, trochanter, and femur light 

 brown ; tibia tan on basal three-fourths, apical fourth black ; tarsus 

 black. Leg 2, length, 2.7 mm. ; coxa dark brown to black ; trochanter 

 light brown ; femur and tibia light brown with apical dark ring ; basal 

 third of basitarsus and of second tarsal segment tan, the remainder 

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

 3.3 mm. ; coxa black ; trochanter light brown ; femur and tibia light 

 brown on basal four-fifths, black on apical fifth ; basal half of basi- 

 tarsus and of second tarsal segment tan, the remainder of these seg- 

 ments, as well as all of tarsal segments 3-5, black ; relation of basi- 

 tarsus to second tarsal segment, 4.6 : i ; calcipala well developed, but 

 not reaching pedisulcus ; pedisulcus well developed at middle of second 

 tarsal segment ; claw with rather blunt, small, submedian tooth (pi. 35, 

 fig- 251). 



Abdomen : Tergite of segment i black, its midregion tan, with 

 short black hairs ; pleurites black, with long tan hairs reaching the 

 fourth segment. Segment 2 black, white-pruinose. Segments 3-5 dull 



