Polycentropus; apex of tarsus of all 3 pairs of legs with a crown of 

 spinules; claws thin, slightly curved; almost as long as tarsi on midlegs and 

 hind legs. 



Anal legs thin at the end; setae of section "a" relatively long, not shorter 

 or slightly shorter than the secondary setae of section "b." Claw thin, bent 

 at almost a right angle at the end; subapical band of spinules distinct; 

 2 or 3 dorsal spinules larger than the others. 



Pupa. Length 6.5 — 10 mm. Antennae reaching segments 5—8. Labrum 

 with rounded anterior margin, sometimes with a small median process, 

 with 2 long and 4 short setae. Mandibles sickle -shaped, less strongly 

 curved than in Plectrocnemia, with blunt end. Wing sheaths reaching 

 segments 5—6; first 4 segments of fore and mid-tarsi (sometimes also of 

 hind tarsi) with natatorial setae. Presegmental plates on segments 3—8, 

 with 4—6 denticles; postsegmental plates on segment 5 with 8—12 denticles. 

 End of body with broad, rounded anal lobes; segment 8 of females with a 

 conical ventral process. 



Pupal case made of loose tissue, covered with sand grains or small 

 stones; anterior and posterior end with filtering sieves. Pupa lying in a 

 cocoon of loose tissue. 

 441 Mode of life and habitats. Larvae predacious, building capturing 

 nets; mainly living in stagnant water, in plant thickets in lakes and flood- 

 land water bodies, also in plant thickets in rivers and rivulets with a slow 

 current. 



Distribution. European USSR, the Caucasus, Siberia, Kamchatka. 

 In addition, Europe, northern Mongolia. 



Key to Species 

 Full-grown larva 



1 (4). Dorsal stripes of head distinct, extending almost to the posterior 



margin; frontoclypeus light in the middle. 



2 (3). Transverse row of dots in the posterior part of the frontoclypeus 



absent, or only indistinct marginal dots present; sclerite light 

 anteriorly in the middle 1. H. picicornis Steph. (p. 500) 



3 (2). Transverse row of dark dots present in posterior part of fronto- 



clypeus; sclerite slightly dark near the posterior margin 



2. H. stagnalis Alb. (p. 508) 



4 (l). Dorsal stripes indistinct, extending from anterior margin to middle 



of head; frontoclypeus dark anteriorly and posteriorly, only an area 

 in the middle light 3. H. dubius Ramb. (p. 508) 



Pupa 



1 (4). Labrum a median anterior process; all 3 setae of clypeus long. 

 Hind tarsi with natatorial setae; ventral process of segment 8 of 

 female pupae relatively long, with a saddle-shaped indentation. at 

 the end. 



499 



