NO. I BLACK FLIES OF GUATEMALA — DALMAT IO5 



tion; segment 2 with 16 spines in transverse row three-fourths the 

 distance from the anterior margin, with median separation ; segments 

 3 and 4 each with 16 spines in transverse row somewhat before the 

 posterior margin, with median separation, the inner three spines on 

 either side of the midline larger than the others ; segments 6 and 7 

 each with uninterrupted transverse row just behind the anterior mar- 

 gin, segment 6 with 50 spines, segment 7 with 40 spines ; segment 8 

 with 42 spines in uninterrupted row behind the anterior margin and 

 with other transverse row of 6 long spines, posterior to the longer 

 row, divided by median space. Ventral surface of abdominal seg- 

 ments : Completely covered wtih granulosity ; all spines anteriorly 

 directed; all transverse rows are situated somewhat in front of the 

 posterior margin of the respective segment ; segment 3 with 4 simple 

 spines in transverse row, the spines well separated from each other, 

 with median space ; segment 4 with 12 simple spines in transverse 

 row, with median separation; segments 5 and 6 each with 8 simple 

 spines in transverse row, with median separation, the outer spine on 

 either side of the row smaller than the others ; segment 7 with similar 

 transverse row to that of segment 3, the spines being somewhat 

 heavier ; outer margin on either side of segment 9 with i bifid and 6 

 simple long hairs. Terminal spines very well developed, cone-shaped, 

 pointed. 



Respiratory apparatus (pi. 36, fig. 279) of each side arising near 

 the anterior corners of the thorax ; composed of 12-15 expanded fila- 

 ments, somewhat saclike, tapered toward the apex, which branch as 

 follows: 1-3-3-1-1 -3-2; six to eight of the filaments have very much 

 narrowed extensions from their apices ; filaments without superficial 

 segmentation, but completely wrinkled in all directions and with 

 microscopic spicules. Maximum length, i.i mm.; average diameter, 



140 jU,. 



Cocoon (pi. 39, fig. 319) : Length of base, 3.0 mm.; maximum 

 width, 1.4 mm.; maximum height, 1.8 mm. Cocoon of wall-pocket 

 type, without collar; case composed of soft, loose threads to which 

 particles of mud and sand have attached ; cocoon with ventral surface 

 convex, in profile, the anterior aperture appearing perpendicular to 

 the anterior section of the base ; rim around anterior aperture not 

 thickened. Cocoon covering only three-fourths of abdomen ; attached 

 along entire base except for a very small anterior section. 



Larva (pi. 40, fig. 359, and pi. 42, fig. 396). — (First description of 

 larva.) Total length, 5.0 mm. Length of head capsule i.i times its 

 width. Width of thorax 1.3 times that of head. First 4 abdominal 

 segments about equal to thorax in width ; segments 5-7 expanded, 



