NO. I BLACK FLIES OF GUATEMALA — DALMAT 243 



segment 5, the distance between them being approximately equal to 

 that of the median space. Terminal spines absent. 



Respiratory apparatus (pi. 38, fig. 308) of each side arising some- 

 what behind the anterior margin of thorax ; each composed of 2 main 

 divisions, which are inflated, having a posterior "tail" where the two 

 elements diverge ; apparatus hornlike, the dorsal element long, club- 

 shaped, with its upper surface somewhat tuberculated near the apex ; 

 the ventral element passes around the anterior aperture of the cocoon, 

 with which it is in close apposition ; all elements of respiratory appara- 

 tus with superficial annulation, more pronounced on dorsal element ; 

 with many longitudinal and transverse folds. Maximum length, 1.5 

 mm. ; maximum width, 0.6 mm. 



Cocoon (pi. 39, fig. 348) : Length of base, 2.4 mm. ; maximum 

 length, 4.2 mm. ; maximum width, 1.6 mm. ; maximum height, 1.6 mm. 

 Cocoon slipper-shaped, with distinct collar and fine parchmentlike 

 texture, threads not visible ; no festoons or prolongations from margin 

 of anterior aperture ; in profile, anterior aperture is at 45 degree angle 

 to base, its rim slightly thickened. Cocoon attached along half of its 

 base ; covers the abdomen and half of the thorax. 



Larva (pi. 41, fig. 386, and pi. 43, fig. 423). — Total length, 7.3 mm. 

 Length of head capsule equal to the width. Width of thorax 1.5 times 

 width of head. Abdominal segments 1-4 approximately 1.3 times 

 width of head ; segments 5-7 somewhat expanded, greatest at segment 

 7 which is 1.4 times the average width of segments 1-4; in profile, the 

 larval form appears similar to that of members of subgenus Dyarella. 

 General color gray to tan, with irregular dark patches on ventrolateral 

 areas of segments 6 and 7. 



Head: Designs on frons-clypeus and epicranial plates shown on 

 plate 41, figure 386. Each cephalic fan with 46-50 pectinate branches, 

 the hairs on these branches being short, simple, and close together, 

 interspersed with longer bifid ones at regular intervals. Mandible with 

 2 to 3 teeth on its inner margin, the most basal one longer than the 

 other two, the apical one blunt ; all three teeth contiguous. Antenna 

 380 /A long, 5-segmented, yellow, just passing the end of the basal 

 stalk of cephalic fan ; segment i>2>3 = 4>5 ; segment 2 with super- 

 ficial division at its middle and with white patches at the midregion 

 and apical end; also with a longitudinal dark-brown patch on each 

 yellow area ; segment i with white patch at base and with longitudinal 

 striations. Submentum with 9 apical teeth, the central one and two 

 outer teeth longer than the others ; teeth triangular in shape, large ; 

 ventrolateral row with 14-15 hairs in an irregular line, almost all bifid 

 except the basal ones ; lateral margin of submentum with 4 toothlike 



