NO. I BLACK FLIES OF GUATEMALA — DALMAT 2/1 



divided into two by a median space ; segment 6 with band composed 

 of comblike groups of spines (3-5 spines per comb) along the anterior 

 margin, with median separation ; segment 7 with transverse row of 

 22-24 simple spines across the anterior margin, divided by median 

 space, and with combs (2-8 spines per comb) lateral to the row of 

 spines and intermixed with them ; segment 8 with transverse row of 

 24 simple spines along the anterior margin, divided by median space, 

 and with combs (2-4 spines per comb) lateral to the row of spines and 

 intermixed with them. Ventral surface of abdominal segments: No 

 granulosity ; all spines are anteriorly directed ; segment 5 with 4 simple 

 spines in transverse row about three-fourths the distance from the an- 

 terior margin, the row divided by median space; segments 6 and 7 

 each with a similar row of spines, the two spines on either side of 

 midline separated more than on segment 5, the distance between them 

 approximately equal to that of the median space ; rarely, the two inner 

 spines on segments 5 and 6 are bifid. Terminal spines absent. 



Respiratory apparatus (pi. 38, fig. 314) of each side arising a little 

 behind the anterior margin of thorax; composed of 2 main elements, 

 the dorsal and ventrolateral, which appear hornlike when viewed from 

 above ; the elements of each side form a broad V, the two arms so 

 curved that the broad surfaces are at an angle of 90 degrees to one 

 another; the elements are so thin that unless they are carefully dis- 

 sected from the cocoon the ventral element may go unnoticed. The 

 dorsal element extends anteriorly from the cocoon for only a short 

 distance; when viewed from above with the aid of only a hand lens, 

 this element is also hardly visible ; the ventrolateral curves around the 

 collar of the cocoon near the anterior aperture and remains contiguous 

 with it along its entire extent, except at its distal extremity where it 

 overlaps with the corresponding arm of the opposite side ; along its 

 inner ventral surface there is a deep groove ; no "tail" extending pos- 

 teriorly from point of divergence of both elements; with superficial 

 annulation and with microscopic spicules. Length of dorsal element, 

 0.9 mm.; length of ventral element, 1.6 mm.; maximum width, 0.4 

 mm. ; strongly compressed dorsoventrally. 



Cocoon (pi. 39, fig. 354) : Length of base, 3.5 mm. ; maximum 

 length, 4.7 mm. ; maximum width, 2.0 mm. ; maximum height, 1.7 mm. 

 Cocoon slipper-shaped, with definite collar; fine parchmentlike tex- 

 ture, threads not visible ; rim around anterior aperture thickened. Co- 

 coon covering abdomen and thorax; attached along posterior half of 

 its base. 



Larva (pi. 41, fig. 392, and pi. 43, fig. 429). — (First description of 

 larva.) Total length, y.y mm. Length of head capsule i.i times its 



