Lateral line on segments 3—8; gills as in larva. Holding apparatus on 

 segments 3— 7, number of spinules: segment III: 2—3; segment IV: 2—9; 

 segment V: 2—3+9; segment VI: 2—4; segment VII: 3—4. 



Dorsal processes of segment 9 with 4 dark setae, 2 of them smaller 

 than the others. Anal rods long, thin, resembling those of Oe. ochracea 

 (Figure 813, B). 



Pupal case 8.0— 10.5 mm long, made of larger sand grains and plant 

 fragments, almost cylindrical, slightly tapering posteriorly, with coarser 

 surface than in larva; both openings sometimes covered with small plant 

 fragments; membranes yellowish brown. Case attached to plants and 

 stones by large disks. 



Mode of life and habitats. Small, eutrophic lakes, littoral and 

 sublittoral; on solid bottom of sand and detritus or silt; sometimes among 

 plants; in creeks or mouths of slow rivers; small floodplain water bodies; 

 ponds. 



Distribution. Northern, western, and central parts of the European 

 USSR; Western and Eastern Siberia, Maritime Territory, Amur region. 

 In addition, Europe, northeastern China. 



4. Oecetis furva Rambur 



Klapalek, 1893:103—107, Figure 28.— Lampert, 1900:205, Figure 81.— 

 Struck, 1900:Figure 43; 1903:Plate III, Figure 14.— Ulmer, 1903:108—109, 

 Figures 32,42.— Thienemann, 1905b:534— 537.— Siltala, 1905:82—90.— 

 Ulmer, 1909:245—246, 309, Figures 372, 454a.— Lestage, 1921:639—646, 

 Figures 221a, d, e, m, 222B, 223.— Lepneva, 1940:210. 



Full-grown larva. Length 7.5— 9.8 mm. Head almost as long as wide, 

 brownish, lighter around eyes (Figure 814). Eyes small. Sensilla of 

 antenna thin but long; seta small, light. Frontoclypeus with short, anterior 

 and long, posterior part; anterior part occupied by 3 pairs of large dots 

 arranged in a circle, dots of posterior pair larger than the others; a small, 

 510 dark stripe at anterior margin before dots; posterior angle with 2 dark 

 spots situated one behind the other (sometimes fused), each spot with 

 2 large, blackish dots. Dorsal stripes pale; 3 dots along posterior part of 

 frontal suture, 2 anterior dots very large; several small, pale dots at base 

 of setae between and before large dots. Four to five dots lateral to 

 coronal suture, large dots on site of lateral stripes and ventrally in 

 posterior part. Gula brownish, trapezoidal, large, separated from occipital 

 foramen by a narrow, light stripe. 



Median anterior-margin seta longer than the others; intermediate 

 anterior-margin seta situated in the angle, large; lateral anterior-margin 

 seta small, thin; anterior frontal seta short, curved inward; intermediate 

 frontal seta moderately long, larger than the others, both latter setae 

 situated lateral to large dot of posterior pair; posterior frontal setae 

 small, thin. Setae 9 and 11 long; seta 7 slightly shorter; seta 10 larger 

 and thicker than 7; seta 14 situated near large dot, long, thick; seta 12 

 m.uch smaller; setae 13, 14, and 16 situated one behind the other further 

 posteriorly near dorsal stripe; seta 17 large. Ventral side: seta 8 small, 

 light; seta 18 smaller, setuliform. 



637 



