membranous, longer and broader than prothorax. Episternum and 

 epimeron of propleuron almost of the same size; trochantin oblong, with 

 a more or less distinct horn-shaped process. Meso- and metapleural 

 sclerites small; episternum larger than epimeron. 



Legs short and weak; midlegs slightly longer than the others; setae of 

 legs short, many of them spinelike; claws with an outer spine near the seta. 



Abdominal segment 9 much narrower than the preceding segments, 

 without dorsal sclerite; anal legs long; anus forming a transverse slit; 

 five anal gills below the dorsal fold, which covers the anus and the base of 

 the anal legs. 



Most abdominal setae small and light, like setules; ventral setae of 

 segment 9 situated on small sclerites. Sclerite "a" of anal legs soft and 

 well marked; sclerite "b" oblong; its 2 distal setae longer than the others; 

 seta of sclerite "c" small; claw strong and short, without basal or dorsal 

 denticles; all 8 setae present. 



Pupa. Male pupae 5— 10 mm long, female pupae 6— 12 mm; antennae 

 shorter than body, reaching segment 3 in male pupae and segments 5—7 in 

 female pupae; first segment with 2—4 dark setae; eyes large. Labrum 

 short and semicircular, with 3 setae laterally at the anterior margin. 

 Mandibles strong and long, geniculate at the base; blade serrated, with 

 3 large teeth; outer setae short, anterior seta shorter than posterior seta 

 and curved; mandibles of pupa folded at rest and their ends project 

 laterally. Wing sheaths short, reaching segments 3—4, pointed; posterior 

 wing sheaths longer than anterior sheaths. Natatorial setae of mid-tarsi 

 thin, dark; dorsal row present on segments 1—3, ventral row on segments 1 

 and 2; a few setae also on the 3rd segment; claws of fore and mid-tarsi 

 curved, dark and strong; claws of hind tarsi weak and almost straight. 



Presegmental plates of holding apparatus present on segments 3—7; 

 postsegmental plates on segment 5; plates and spinules yellowish; each 

 plate with 8 or 9 spinules; spinules on presegmental plates situated in the 

 middle of the plates, near the posterior margin on postsegmental plates. 

 Anal lobes absent; end of body of female pupa conical, blunt; male genitalia 

 distinct, i. e., lower appendages and sheath of penis. 



Pupal case oblong, elliptical, with a covering of small stones or sand 

 grains, 10— 18 mm long; pupa lying in a thick gray cocoon which is attached 

 in many points to the wall of the case. 



Mode of life and habitats. Cool running water and stony 

 bottom; larvae and pupae on the underside of stones; eyes therefore small 

 and the very sensitive and movable labrum membranous; some species 

 occur in caves. 



Distribution. USSR: European and Asian parts, mainly in 

 mountainous regions; cosmopolitan. 



Key to Genera 



Full-grown larva 



1 (2). Anterior margin of frontoclypeus with a deep asymmetrical 



indentation; coxa of forelegs distodorsally with a large long 



spinelike process near the strong anterior seta 



4. Chimarrha Steph. (p. 421) 



409 



