NO. I BLACK FLIES OF GUATEMALA — DALMAT 101 



saclike branches, 3 of them with 2 filaments each extending from the 

 apex, the fourth with only a single filament ; all branches and filaments 

 show annulations and minute spicules. Maximum length of one 

 branch, 3.6 mm. ; maximum width of branch, 0.3 mm. 



Cocoon (pi. 39, fig. 318) : Length of base, 5.3 mm. ; maximum 

 width, 3.7 mm. ; maximum height, 2.1 mm. Cocoon of wall-pocket 

 type, without collar ; rim around anterior aperture not thickened, no 

 dorsal prolongation ; case composed of soft matrix with the threads 

 loosely grouped and with particles of earth and other material. Cocoon 

 covers the abdomen and one-fourth of the thorax ; attached along the 

 entire base. 



Larva (pi. 40, fig. 358, and pi. 42, fig. 395). — (First description 

 of larva.) Total length, 8.3 mm. Length of head capsule i.i times 

 its width. Width of thorax 1.4 times the width of head. First four 

 abdominal segments i.i times the width of head; segments 5-7 ex- 

 panded, greatest at segment 6 which is 1.4 times the width of seg- 

 ments 1-4 ; general body shape like that of aguirrei. General color tan, 

 the ventral surface of pseudopod gray; ventrolateral regions of seg- 

 ments 6 and 7 usually with long dark patches. 



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

 plate 40, figure 358. Each cephalic fan with 24 pectinate branches, 

 the hairs on these branches simple, rather long and close together, not 

 interspersed with hairs of other types. Mandible with 29-32 teeth 

 along its inner margin, some of the teeth at times appearing double- 

 pointed, others appearing truncate ; most-distal tooth longer than any 

 of the others. Antenna 520 /x long, 4-segmented, light yellow, just 

 reaching the end of the basal stalk of the cephalic fan ; segment 2 is 

 I.I times the length of segment 3 which is 1.5 times that of segment 

 I ; no transverse striations. Submentum with 13 apical teeth arranged 

 in 3 projecting groups as in agiiirrci, the central group with three 

 teeth, each of the lateral groups with five teeth; ventrolateral row 

 with 6 hairs, at times in irregular row, the most distal hair bifid, the 

 others simple; lateral margin of submentum with 15 toothlike serra- 

 tions. Occipital cleft minute, triangular in shape (pi. 42, fig. 395). 



Thorax and Abdomen : Pseudopod (thoracic proleg) with 27-30 

 rows of hooks on its apex ; postclypeal sclerites well sclerotized, heavily 

 pigmented, long, wider at outer extremity, almost meeting at midline. 

 Posterior sucker with 95-100 rows of hooks. Anal gills three in num- 

 ber, very broad at base, tapered toward apex, longer than in aguirrei. 

 Anterior arms of X-shaped sclerite short, poorly sclerotized ; pig- 

 mented patch occupies all the space between them ; posterior arms well 

 sclerotized, extending only to lateral margins of segment; no rectal 



