Case 19 — 22 mm long (Figure 465), straight or slightly curved, made of 

 large sand grains, tapering posteriorly, with flat ventral surface; dorsal 

 wall projecting in form of a hood; posterior end rounded, with fine sand 

 grains around opening. Posterior end of case of young larvae usually 

 consisting of longitudinally or obliquely arranged plant particles. 



Mode of life and habitats. Small, cool, clear brooks with a 

 stony or sandy-stony bottom and a moderate current. Pupae occur often 

 in large numbers, in rows. 



Distribution. Western and southwestern parts of the European 

 USSR. In addition. Northern and Central Europe. 



4. Potamophylax rotundipennis Brauer 



Walser, 1864: 68 - 69. - Klapalek, 1893: 16-20, Figure 4i-g. -Struck, 

 1900: 13 (separ.). Figures 16, 17; 1903: 98-99, Plate II, Figure 8. - 

 Siltala, 1903a: 27-30, Figure 8. - Ulmer, 1903:65-66, Figure J, - 

 Siltala, 1904c: 66. -Ulmer, 1909:266, Figure 395. - Lestage, 1921:766, 

 770-772, 774, Figures 274, 275. 



Full-grown larva. Length 17 — 19 mm. Head (Figure 466) broadly oval, 

 pale yellowish brown, with dark, chestnut brown punctation; anterior margin 

 of frontoclypeus narrowly golden brown; slightly brownish spots at margin 

 near tentorial pits, a narrow golden stripe lateral to frontal sutures further 

 posteriorly; punctation of wedge-shaped pattern on brownish background; 

 posterior angle and greater part of surface light. A reddish brown stripe 

 between eye and anterior margin, including base of antennae; short, 

 transverse rows of dots lateral to epicranial suture; sides of head with 

 longitudinal rows of dots behind eye. Ventral surface smoky yellow in 

 middle, whitish yellow anteriorly, with groups of dots laterally near 

 occipital foramen posteriorly; middle with streaks from 2 darker dots. 

 Gula light, with brownish stripes laterally (Figure 467), 



Large setae reddish brown, thinner than inP. stellatus; median 

 and intermediate anterior-margin setae of about same length, lateral seta 

 short, curved, light; anterior frontal seta thinner and procumbent; middle 

 frontal setae larger than usual, longer and thicker than anterior margin 

 setae; posterior frontal setae thin, moderately long, yellow; setae 9 and 14 

 long, thick, 14 markedly larger; setae 10, 11, and 13 small, thin, 11 light, 

 curved anteriorly; seta 12 short, thin, yellow, slightly larger than 13; 

 seta 15 brown, thin, long, shorter than 9; seta 16 thin, small, procumbent; 

 seta 17 firm, moderately long, shorter than middle frontal seta. 



Labrum darker than head, reddish brown, with a dark spot behind 

 median pit, slightly displaced to the right. Left mandible with a large tooth 

 and 2 oval tooth-shaped processes dorsal to middle tooth, a large tooth 

 ventral to it; right mandible with 3 large teeth in a ow dorsal to middle 

 tooth, a small tooth ventral to it. 



Sclerites of cardo in form of narrow, transverse rods, yellowish brown 

 „„j. in middle, black laterally, with wide black inner margin. Submentum and 

 stipes brown, darker than head; mentum dark reddish brown. 



330 



