NO. I BLACK FLIES OF GUATEMALA — DALMAT 257 



the two spines on either side of midHne separated more than on seg- 

 ment 5, the distance between them being approximately equal to that 

 of the median space. Terminal spines absent. 



Respiratory apparatus (pi. 38, fig. 311) of each side arising a little 

 behind the anterior margin of the thorax ; composed of 2 main ele- 

 ments which are inflated, and a "tail" extending posteriorly from the 

 point of divergence of the two elements ; there is a very massive, horn- 

 like dorsal element, a smaller ventral element, and a short, well- 

 formed, tail-like posterior extension of the dorsal element which is 

 directed mesad ; dorsal element with concavity on its upper surface ; 

 with superficial annulation, each ring with longitudinal folds. Maxi- 

 mum length (dorsal element), 2.3 mm. ; maximum diameter, 0.4 mm. 



Cocoon (pi. 39, fig. 351) : Length of base, 3.5 mm, ; greatest length, 

 4.2 mm.; greatest width, 1.9 mm.; greatest height, 1.9 mm. Cocoon 

 slipper-shaped, with definite collar ; fine parchmentlike texture, 

 threads not visible ; rim around anterior aperture somewhat thickened. 

 Cocoon covering abdomen and three-fourths of thorax ; attached along 

 posterior half of its base. 



Larva (pi. 41, fig. 389, and pi. 43, fig. 426). — (First description of 

 larva.) Total length, 7.0 mm. Width of head capsule equal to its 

 length. Width of thorax 1.6 times that of head. Width of abdominal 

 segments 1-3 somewhat less than width of thorax, all three subequal; 

 segment 4 equal in width to thorax ; segments 5-8 expanded, greatest 

 on segments 6 and 7 which are 1.5 times width of segments 1-4; cross 

 section and profile are the same as for capricornis. General color gray, 

 with dark irregular patches on ventrolateral regions of segments 7 

 and 8. 



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

 plate 41, figure 389. Each cephalic fan with 39-40 pectinate branches, 

 the hairs on the branches simple, short, close together, interspersed 

 at regular intervals with longer, stouter, bifid hairs. Mandible with 

 2 teeth on its inner margin, these emerging from a common base, the 

 more distal tooth somewhat larger. Antenna 400 /x, long, 5-segmented, 

 light yellow, surpassing the basal stalk of cephalic fan ; segment 

 i>2 = 3<4; segment 2 superficially divided in two near its middle, 

 the division being in the middle of a white patch ; no other white 

 patches on antenna ; segment i with longitudinal striations. Submen- 

 tum with 9 apical teeth, in shape like one-half of a hexagon, the cen- 

 tral tooth, and the outermost tooth on either side larger than the 

 others; ventrolateral row composed of approximately 21 hairs ar- 

 ranged irregularly in groups of one, two, or three, all hairs appearing 

 bifid ; lateral margin of submentum with 7 toothlike indentations. 



