NO. I BLACK FLIES OF GUATEMALA DALMAT 201 



short tan hairs and last segment with black hairs. Sternites black with 

 white pruinosity. 



Genitalia: Sidepiece (pi. 25, fig. 6']') almost square, very slightly 

 wider than long ; dorsal opening occupying basal half of sidepiece. 

 Length of clasper (pi. 25, fig. dj^ about four times its width, its mar- 

 gins being sinuous, with only very slight convexities ; clasper about of 

 equal width throughout ; a sclerotized dorsal ridge extends from the 

 dorsal opening on the clasper to the apical spine ; apex blunt, with a 

 single, well-formed spine near margin. Body of adminiculum (pi. 25, 

 fig. 68) rectangular in shape, about twice as long as wide ; along the 

 body on the ventral surface is a pronounced keel which is clothed with 

 numerous hairs ; basal prolongations broad, their apices greatly ex- 

 panded, somewhat spatulate, and well sclerotized. Arms of admi- 

 niculum (pi. 25, fig. 69) with approximately 30 teeth arranged in 

 linear fashion ; lateral plate almost triangular in shape, not heavily 

 sclerotized. 



Female (pi. 32, figs. 187-189, and pi. 35, fig. 243). — 4.1 mm. long. 



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

 three times the base. Antenna 820 ^ long, ii-segmented, tapering; 

 segment 3>i-f-2, ii = i-|-2, ii>3; segment 1 1 rather blunt ; scape 

 and pedicel light brown, the flagellum dark brown to black. Palpi 

 dark brown. Frons black, white-pruinose, with 3 rows of black hairs 

 around periphery. Qypeus and occipital region black, white-pruinose, 

 covered with long black hairs. Cornuae of buccopharyngeal apparatus 

 with apical half sclerotized, bifurcated ; median space hyaline, with 7 

 irregular rows of very small scalelike teeth. 



Thorax : Mesonotum blue black, completely white-pruinose with 

 no longitudinal stripes or bands ; long, narrow, yellow, scalelike hairs, 

 in packets of 2-5, over entire mesonotum ; short black hairs all over 

 mesonotum, longer on prescutellar region. Humeral angles velvety 

 brown to black, with white pruinosity. Scutellum black, with numer- 

 ous yellowish scalelike hairs as on mesonotum, and with several long 

 black hairs. Postnotum velvety brown to black, with white pruinosity. 

 Pleura evenly brown to black, with white pruinosity. Wings, 4.4 mm. 

 long and 1.9 mm. wide; relation of length of body to wing, i : i.i ; 

 Sc pilose except for very short apical portion ; Ri completely pilose, 

 the apical half with spines also, at times with short interruption in 

 hairs near base ; R2+3 completely pilose ; Cu2 arcuate ; discal cell absent. 



Legs: Leg i, length, 4.9 mm.; coxa, trochanter, and femur light 

 brown ; tibia black, with very narrow light-brown basal ring ; tarsus 

 black. Leg 2, length, 4.2 mm. ; coxa dark brown ; trochanter brown, 

 the inner surface black ; femur brown ; tibia varying from brown to 



