Number and arrangement of gills of 

 A . zone 11a 



Segment 



Dorsal 



Ventral 



1 



1 





2 



1 

 1 



1 



3 



1 



1 



1 



4 



1 



1 



5 



1 



1 



6 





1 



Sclerite "b" of anal legs dark brown, with dark, keel-shaped, serrated 

 tubercles. Distal median seta thick (thickest of the whole body), black, 

 longer than medioanal seta of segment 9; neighboring seta much shorter 

 and thinner; lateral seta moderately long, thin; subapical seta of median 

 margin thin; all 3 setae black; ventral seta short, blackish. Sclerite "c" 

 light brown; lateral margin wide, black, with large median process; seta 

 small, light brown. Claw yellowish brown basally, dark brown apically, 

 with reddish brown end; median seta 1 situated in basal part, short, strong; 

 seta 2 situated laterally, near end of suture, moderately long; seta 6 smaller, 

 situated near distal raargin of suture; seta 3 situated on median side of 

 distal part, moderately long; ventral seta 7 thin, situated on sclerite; seta 

 8 slightly thicker, situated on membrane near margin; seta 5 small, situated 

 on sclerite near 8; seta 4 small, situated on median side of ventral area, 

 on sclerite; all 4 setae light. 



Case 8—9 mm long, slightly curved, tapering posteriorly, made of small 

 and medium-sized sand grains, smoothly arranged; sides, sometimes also dor- 

 sal side, with isolated sand grains, smoothly arranged; anterior opening with 

 dorsal hood, directed ventrally; several large sand grains on lateral margin, also 

 dorsally before pupation; posterior end rounded, closed by membrane with 

 an irregular hold (Figure 213). 



Mode of life and habitats. Springs; small, spring-fed brooks; 

 mountain brooks and rivulets. 



Distribution. Northern, northwestern, and western parts of the 

 European USSR, Altai, northern Kazakhstan, Western and Eastern Siberia, 

 Maritime Territory and Amur Region. In addition. Northern Europe 

 (Scandinavia), Mongolia, Greenland, North America. 



6. Apatanla majuscula McLachlan 



Levanidova, 1962:190-192, Figure 1 . 



Full-grown larva. Length 9—10 mm. Head (Figure 214, A) mainly dark 

 on dorsal side, rust brown, covered with blunt, rarely pointed tubercles; 



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