96 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



transverse row before the posterior margin, the row divided in two 

 by a median separation ; segment 4 also with irregular row of about 

 90 posteriorly directed small spines just behind the anterior margin, 

 without median separation ; segments 5-8 each with an uninterrupted 

 row of spines just posterior to the anterior margin, segment 5 with 

 102 spines, segment 6 with 104, segment 7 with 98, and segment 8 

 with 70. Ventral surface of abdominal segments : Entire ventral sur- 

 face with granulosity; all spines are anteriorly directed, and all the 

 rows are located a little before the posterior margin of the respective 

 segment ; segment 4 with a single simple spine on either side of mid- 

 line, well separated by a median space ; segments 5-7 each with 4 sim- 

 ple spines in a transverse row, all spines in the row well separated 

 from one another; each of the lateral margins of segment 9 with 2 

 bifid and 3 simple long hairs. Terminal spines very well developed, 

 about 150 /u. long. 



Respiratory apparatus (pi. 36, fig. 277) of each side arising a little 

 behind the anterior margin of the thorax ; composed of 12-13 filaments 

 that branch as follows: 2-2-2-2-2-2-1; the single filament is much 

 shorter than any of the others ; filaments emerge in one plane like the 

 spokes of a wheel ; the apices of all filaments pointed ; with superficial 

 annulations and minute spicules. Maximum length, 1.3 mm. ; average 

 diameter, 80 fi. 



Cocoon (pi. 39, fig. 317) : Length of base, 4.0 mm.; maximum 

 width, 3.0 mm.; maximum height, 1.2 mm. Cocoon of wall-pocket 

 type, without collar; case composed of grouping of threads with at- 

 tached particles of mud and other material ; the case is very soft, not 

 having a regular shape, and appears to cling to the pupa ; this species 

 is found in sluggish water running over mud. Cocoon covers the ab- 

 domen and one-fourth of the thorax ; barely attached at the posterior 

 end of its base. 



Larva (pi. 40, fig. 357, and pi. 42, fig. 394). — (First description of 

 larva.) Total length, 5.9 mm. Length of head 1.2 times its width. 

 Width of thorax 1.3 times width of head. Abdominal segments 1-4 

 approximately 1.2 times width of head ; segments 5-7 expanded, great- 

 est at segment 6 which is 1.4 times the width of segments 1-4 ; general 

 body shape like that of aguirrei. General color tan, without dark 

 patches on ventrolateral regions of segments 6 and 7. 



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

 plate 40, figure 357. Each cephalic fan with 25 pectinate branches, the 

 hairs on these branches simple, long, and close together, without hairs 

 of other types intermixed. Mandible with 25 teeth along its inner 

 margin, the distal tooth very much greater in size than any of the 



