NO. I BLACK FLIES OF GUATEMALA — DALMAT 233 



margin, and with combs lateral to both extremities of the row ; seg- 

 ment 9 with 3 transverse rows of very small spines, without median 

 separation, crossing on the anterior part of the segment. Ventral sur- 

 face of abdominal segments : No granulosity ; all spines are anteriorly 

 directed ; segment 4 with transverse row of 6 simple spines across the 

 posterior margin, with median separation ; segment 5 with 4 bifid 

 spines in transverse row, with median separation ; segments 6 and 7 

 each with a single bifid spine on either side of midline, the two spines 

 on each segment well separated ; all spines on segments 5-7 situated 

 somewhat before the posterior margin of the respective segment. 

 Terminal spines very small. 



Respiratory apparatus (pi. 37, fig. 306) of each side arising slightly 

 behind the anterior border of thorax ; from a narrow base 2 very wide, 

 inflated tubes divide off, each of these with at least another subdivision 

 closer to its apex; more-dorsal element with numerous rather long 

 hairs, present from where it branches from ventral element almost to 

 its apex; elements with transverse wrinkles, but without superficial 

 segmentation or minute spicules. Maximum length (dorsal element), 

 2.0 mm. ; maximum width, 700 /*. 



Cocoon (pi. 39, fig. 346) : Length of base, 4.9 mm.; maximum 

 width, 3.5 mm.; maximum height, 1.4 mm. Cocoon of wall-pocket 

 type, with definite collar; texture of case parchmentlike, the threads 

 rather loose and easily visible ; lateral margins expanded to form 

 winglike structures that give the cocoon an oval appearance when 

 viewed from above; wings extend and join each other anteriorly in 

 the form of a broad ribbon, which gives the cocoon the appearance of 

 having a slight collar. Cocoon covers the abdomen only; attached 

 along the posterior half of its base. 



Larva (pi. 41, fig. 384, and pi. 43, fig. 421). — Total length, 6.0- 

 6.3 mm. Length of head capsule i.i times its width. Width of thorax 

 1.3 times width of head. First 4 abdominal segments 1. 1 times width 

 of head; segments 5-7 expanded, widest at segment 6 which is 1.7 

 times width of segments 1-4; body with same general shape as that 

 of metallicum. General color dark gray ; abdominal segments at times 

 with tannish cast ; segments 4-8 milky gray on ventral surface. 



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

 plate 41, figure 384. Each cephalic fan with 44-50 pectinate branches, 

 the hairs on these branches simple, short, well separated, like minute 

 spines, not interspersed with hairs of other types. Mandible with 2 

 teeth on its inner margin, both sharp-pointed, appearing to emerge 

 from the same base ; the apical tooth somewhat more than twice the 

 length of the basal one, neither very long. Antenna 380 /x long, 4- 



