NO. I BLACK FLIES OF GUATEMALA DALMAT 137 



yellow, the pleurites somewhat darker, with narrow band of white 

 pruinosity along anterior margin, with short black hairs. Segment 3 

 yellow. All other segments brown, covered with short black hairs ; 

 pleurites with zones of lighter pruinosity. Sternites yellow gray. 



Genitalia: Sidepiece (pi. 23, fig. 31) somewhat conical in shape, 

 longer than wide, the apex broader than the base ; dorsal opening occu- 

 pying less than half the sidepiece. Clasper (pi. 23, fig. 31) shorter 

 than the sidepiece, somewhat rectangular in shape, the distal end 

 broader than the base ; outer apical angle rounded and somewhat pro- 

 truding, inner apical angle rather sharp-pointed, with one terminal 

 spine at very apex. Body of adminiculum (pi. 23, fig. 33) somewhat 

 pyramidal in shape, its apex rounded ; short spines and longer hairs 

 over entire surface ; basal processes short, slender, the tips pointed and 

 sclerotized, forming angle with the outer basal angles of the body of 

 adminiculum. Adminicular arms (pi. 23, fig. 32) with about 15 teeth, 

 the basal one long, narrow, and sharply pointed, the more-apical ones 

 short and blunt ; lateral plate long, slender, somewhat sclerotized. 



Female (pi. 29, figs. 148-150, and pi. 35, fig. 260). — 2.4 mm. long. 



Head : Dichoptic. Eyes black ; base of fronto-ocular triangle equal 

 to the height. Antenna 430 fi long, 11 -segmented, slightly tapering; 

 segment 3<i-|-2, 3 = 4-1-5, 3>ii; light brown, the flagellum being 

 somewhat darker than the scape and pedicel. Palpi black. Frons and 

 clypeus black, white-pruinose, with few black hairs and some tan ones. 

 Occipital region black, covered with both black and tan hairs. Cornuae 

 of buccopharyngeal apparatus well sclerotized, very wide, and bifur- 

 cated at ends; median space very slightly sclerotized, and somewhat 

 serrate along its margin. 



Thorax : Mesonotum yellow to orange, with 2 narrow bands of 

 white pruinosity, well separated, one on either side of midline, extend- 

 ing from the anterior margin to the posterior region where it unites 

 with the white pruinosity of the prescutellar area ; lateral margins also 

 white-pruinose ; long, narrow, yellow, scalelike hairs over entire 

 mesonotum, more numerous on periphery ; short black hairs over en- 

 tire mesonotum, somewhat longer on prescutellar region. Humeral 

 angles yellow, white-pruinose, with yellow hairs. Scutellum pale yel- 

 low, with some appressed, yellow, scalelike hairs and several long, 

 strong, black hairs. Postnotum dark brown, white-pruinose, devoid of 

 hairs. Pleura yellow, white-pruinose. Stem of halter tan ; the knob 

 pale yellow, almost white, cup-shaped. Wings, 2.6 mm. long and i.o 

 mm. wide; relation of body length to wing, 1:1.1; Sc pilose along 

 basal three-fourths ; Ri completely pilose and with spines on apical 

 half ; R2+3 pilose except for very small basal section ; Cuo arcuate ; 

 discal cell absent. 



