321 



4 (l). Case made of secretion or secretion and algae, light, brownish 



yellow or dark and blackish; covering of mineral particles absent. 



5 (8). Anterior -margin setae on labrum absent; case flat, dorsoventrally 



compressed, light, brownish yellow, attached to the substrate with 

 its broad side, by disks near the anterior and posterior end of the 

 case. 



6 (7). Basal setae of mandibles situated behind each other; shorter distal 



seta projecting outward, case oval, broader in the middle; both 

 ends of the case rounded and similar. . . 1. Agraylea Curt. (p. 352) 



7 (6). Basal setae of mandibles arranged obliquely; shorter distoventral 



seta curved and directed forward; case jug- shaped 



3. Oxyethira Eat. (p. 373) 



8 (5). Labrum with one or two pairs of anterior -margin setae; case of 



different form. 



9 (lO). Labrum with almost straight anterior margin (Figure 462) and a 



narrower projecting posterior margin; two pairs of small, anterior- 

 margin setae; mandibles short; case blackish brown, with longi- 

 tudinal dorsal ridges 5. Orthotrichia Eat. (p.39l) 



10 (9). Labrum with one pair of widely separated anterior -margin setae; 



case sac-shaped, like a pumpkin seed. . . 6. Ithytrichia Eat. (p. 399) 



1. Genus Agraylea Curtis 



Full-grown larva. Length 4.5—5.5 mm. Head sutures not well marked; 

 only a coronal suture and a beginning of frontal sutures (in the 5th stage); 

 distal ends of frontal sutures and ventral sutures absent. Labrum short 

 and broad; setae 5 and 6 several times as long as the labrum. Left 

 mandible with projecting blade, without teeth; small denticles present only 

 near the distal end of the mandible; right mandible without teeth, which are 

 replaced by two tubercles near the distal end; median margin of mandible 

 with a membranous part. Prothorax shorter than meso- and metathorax; 

 only median sternite of prothorax present. Femur of forelegs short, with 

 a large basal process at the ventral margin; distal process of tibia with 

 spinelike setae and other characteristic appendages. 



Abdominal segment 1 much larger than metathorax; height and breadth 

 of abdomen increasing gradually toward segments 4 and 5, then decreasing 

 gradually; dorsal medioanal seta of posterior abdominal segments long; 

 dorsal sclerite of abdominal segment 9 trapezoidal; anal legs short, basal 

 part of claw larger than distal part; end of claw bent at a right angle, 

 without dorsal denticles. 



Case oblong-oval, broader in the middle than at the ends, made of 

 secretion and algae. 



Pupa. Labrum rounded anteriorly; both pairs of anterior-margin setae 

 absent. Mandibles long, with a finely toothed blade in the weakly or strongly 

 curved distal part. Natatorial setae situated at the margin of tarsal 

 segments 1—3 of midlegs. Presegmental plates of the holding apparatus 

 much larger than postsegmental plates; number of spinules varying in the 

 different species. The pupal case is directed to the substrate with its broad 



352 



