seta 3 dark reddish brown, situated subdorsally on inner side of distal 

 part; seta 2 light grayish, situated dorsally at end of suture; seta 6 

 situated near end of suture, brownish, thin; ventrobasal setae 7 and 8 

 thick, light, situated near margin; seta 5 small, situated laterally nearby; 

 seta 4 also small, light situated near the opposite margin of sclerite. 



Case 8— 9 mm, made of small sand grains, slightly curved, narrower 

 posteriorly, with flattened ventral side; anterior part with several large 

 sand grains laterally (Figure 207); anterior opening wide directed ventrally; 

 posterior opening covered by membrane with a large hole. 



Mode of life and habitats. Open littoral zone of lakes, on stones, 

 sand and stones, pebbles, rarely on sand, at a depth of 0,2—6.0 m, isolated 

 specimens as deep as 30 m. In rivers and rivulets close to the bank, on 

 solid bottom. 



Distribution. Northern part of the European USSR (Kola Peninsula, 

 Lake Umbozero, Lake Vud-Yarvi, Arkhangelsk Region, Northern Urals, 

 Western Siberia, Altai (Lake Teletskoe, central Altai). In addition, 

 northern Europe (Finland, Sweden, Norway), North America. 



5. Apatania zonella Zetterstedt 



Siltala, 1908:19-21.- Levanidova, 1960 : 41 9-421 , Figures 8-9. 



Full-grown larva. Length 8—10 mm. Head (Figure 208, A) blackish 

 brown dorsally, blackish near tentorial pit and at posterior angle of 

 frontoclypeus, less dark in the middle='=; dark, rounded tubercles anteriorly 

 and in the middle, becoming smaller near smooth posterior part, with 

 bairlike apical spinules or being replaced by spinules on smooth surface. 

 Frontoclypeus with 3 large, chestnut brown dots lateral to median pit; 

 middle with 2 similar dots ; posterior part with smaller, distinct, brownish dots 

 on area of the wedge-shaped pattern. Dots less distinct lateral to posterior 

 branch of frontal sutures and coronal suture; large brown dots behind the 

 eye; spinules between dots wider, with asymmetrical apex. Ventral surface 

 of head mainly reticulate, its lateral and median parts chestnut brown; 

 small, thick spinules near gular suture. Gula broad, short (Figure 208, B), 

 with curved sides; tubercles few, brownish; pregula forming a narrow, 

 transverse, dark reddish brown stripe. 



Intermediate and median anterior -mar gin setae black, thick, slightly 

 curved, the former larger than the latter; lateral seta light, short, curved 

 inward; anterior frontal seta the same, slightly yellowish; middle frontal 

 seta situated near tentorial pit, smaller and thinner; posterior frontal seta 

 short, dark brown, thin; 2 3—29 secondary setae laterally in anterior part, 

 and 13—15 posteriorly along frontal sutures, most of them brownish, small; 

 some of them larger, dark brown, or light. Seta 7 black, thick, moderately 

 long; seta 9 black, long, thick; seta 14 larger; seta 10 situated before the 

 eye, short, light; seta 11 thin, short, brownish, at level of middle of eye; 

 seta 12 situated behind the eye, short, dark brown; small seta 13 situated 

 lateral to and near 14; seta 15 almost half as long as 14, situated behind 

 14, thin, blackish brown; seta 16 situated behind 15, brownish, small; seta 

 17 short, thick, brown basally, filiform apically; 29—30 very small, thin, 



" Specimens from Novaya Zemlya are darker. 



158 



