NO. I BLACK FLIES OF GUATEMALA — DALMAT 189 



is approximately equal to that of the median space. Terminal spines 

 absent. 



Respiratory apparatus (pi. 37, fig. 296) of each side arising at the 

 humeral angles ; composed of 12 filaments which branch in groups as 

 follows: 5-5-1-1. Maximum length of filaments, 1.8 mm., about 0.36 

 times the length of the cocoon ; average diameter, 24 [x. ; filaments with 

 undulations along surface and covered with microscopic spicules. 



Cocoon (pi. 39, fig. 336) : Length of base, 4.5 mm. ; maximum 

 length, 5.0 mm.; greatest width, 2.5 mm.; greatest height, 2.1 mm. 

 Cocoon slipper-shaped, with distinct collar and fine parchmentlike 

 texture, threads not visible ; without festoons extending from anterior 

 aperture, but with prolongations that extend anteriorly from the ven- 

 tral part of the rim around the anterior aperture ; entire rim somewhat 

 reinforced. Cocoon covering abdomen only. 



Larva (pi. 40, fig. 374, and pi. 42, fig. 411). — Total length, 8.6- 

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

 1.4 times head. Abdominal segments 1-4 gradually widening from 

 segment i, which is about the width of the thorax, to segment 4, which 

 is 1 .3 times the width of thorax ; segments 5-7 somewhat expanded, 

 seventh segment 1.4 times average width of segments 1-4. In profile, 

 like larvae of mathesoni, acatenangoensis, and other species of this 

 subgenus. General color yellow, with gray markings ; transverse 

 black marking on thorax just interior to the base of each histoblast. 



Head: Shield-shaped design occupying posterior half of frons- 

 clypeus, a darker form found within the larger design at its posterior 

 end, somewhat in the form of an inverted funnel ; also 6 small dark 

 spots along midline of frons-clypeus, near anterior end of shield- 

 shaped design (pi. 40, fig. 374) ; epicranial plates light, with approxi- 

 mately 7 dark markings (pi. 40, fig. 374). Each cephalic fan with 

 44-50 pectinate branches ; small hairs of each branch simple, close 

 together, with heavier hairs interspersed at regular intervals. Mandi- 

 ble with only i well-formed tooth along its inner margin, another 

 aborted tooth just visible at base of large tooth, and another indication 

 of a possible tooth farther toward the base of the mandible. Antenna 

 490 IX long, yellow to light brown, 4-segmented, surpassing the basal 

 stalk of cephalic fan ; segment 2 with 2 clear areas that divide the 

 segment into 5 color bands ; segment 2 also with 2 superficial inden- 

 tations that give it the appearance of being 3 distinct segments ; seg- 

 ment 2>i>3. Submentum with 9 apical teeth, triangular in form, 

 the central one larger than the others ; ventrolateral row composed 

 of 8- 1 1 hairs usually in straight line, all generally bifid except the basal 

 two which are simple ; at times, hairs 4-6 are trifid, and the third and 



