(Figure 820^ A) slightly concave laterally, blade serrated, with 3 large 

 denticles in the middle: lateral setae short, close together. 



Wing sheaths narrow, long, anterior sheaths reaching abdominal segments 

 7 — 8. Tibiae without natatorial setae: fore and mid-tarsi natatorial, with 

 dense rows of setae. 



Gills as in larva, larger on anterior than on posterior segments. Holding" 

 apparatus on segments 3 — 7: number of denticles: segment 111:2 — 4: segment 

 IV:2— 5: segment V:2— 5 + 15—18: segment VI:2— 6; segment VII:2— 4. Lateral 

 line thin, with small, grayish setae on segments 3 — 8. Processes of segment 

 9 with 4 dark setae in the male pupa, 2 of the setae snaall, much shorter than 

 the other 2 . Anal rods as inOe. ochracea, thin, long, basal part almost 

 3 times as long as apical part: 3 median spinules at curvature in the male 

 pupa: one seta distal to spinules on left rod, 3 such setae on right rod, one 

 seta laterally at curvature, 3 subapical setae; the median setae and spinules 

 at curvature are slightly more numerous in female pupa (Figure 820, C). 

 Penis sheath bilobed, lobes of genitalia long, rodlike (Figure 820, B). 



FIGURE 821. Oecetis <p. 1, larva nova: Head, dorsal (A) and ventral (B) 



Case to 12 mm long, straight, ends sometimes slightly tapering, made of 

 plant fragments; anterior membrane with a round hole, posterior meinbrane 

 with a wide transverse slit. Attachment by disks at both ends. 



Mode of life and habitats. Usually in vegetation in small, sunlit 

 water bodies: sometimes numerous in ponds. 



Distribution. Northwestern, central, and southern parts of the 

 European USSR, Ciscaucasia, Western Siberia (rare). Maritime Territory. 

 In addition. Central and Northern Europe, Iran. 



5. Oecetis sp. 1 , larva nova* 



Full-grown larva. Length 8— 9 mm. Head (Figure 821, A) mainly light 

 brown, with whitish yellow periocular and anterior lateral areas. Anterior 

 part of frontoclypeus with 3 pairs of dots, those of posterior pair closer 

 together; posterior angle with 2 large dots and a group of small dots. 



Lake Kurgal'dzhin, 20 June 1950,2 larvae, 1 pupa, collected by S. 



643 



Tvutenk'ov. 



