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Sclerite "c" whitish yellow, with broad, indistinct, reddish brown, lateral 

 margin; seta small, light. Claw yellowish basally, reddish brown apically; 

 seta 1 situated in middle of basal part, thick, light, relatively large; seta 3 

 situated in apical part, longer and thinner; seta 2 situated dorsally near end 

 of suture; seta 6 situated near suture, small, thin, light; ventral setae 

 7 and 8 light, large; seta 5 smaller, situated laterally between 7 and 8; 

 seta 4 small, light, situated ventrally near the margin. 



Case 9— 10 mm long, made of sand grains, narrower posteriorly, flattened 

 dorsoventrally, with large dorsal hood anteriorly; larger sand grains at 

 the sides and around the anterior opening; posterior end covered by 

 membrane with a round central hole (Figure 189). 



Mode of life and habitats. Cool, clear water, streams, brooks 

 and rivulets, larger rivers, rapids, open shore of lakes, on a bottom of stone, 

 and sand with stones; in streams in the North, sometimes on firm sandy 

 bottom overgrown with mosses (Font in al i s sp. and H i p pu r i s sp.). 



Distribution. Northern and northwestern parts of the European USSR. 

 In addition, Europe, especially Finland, Poland, Sweden, Norway, England. 



2. Apatamia subtilis Martynov 

 Martynov, 1926:44—45. 



Full-grown larva. Length 7— 8 mm. Head (Figure 190, A) mainly chestnut 

 brown dorsally and laterally before and behind eye; large, light brown spots 

 lateral to coronal suture; a narrow, whitish brown stripe near occipital 

 foramen; eyes situated on large, light, whitish area; ventral surface mainly 

 brown, dark brown laterally, light brown anteriorly, with large, whitish, brown 

 spots near occipital foramen. Frontoclypeus with large, sharply defined 

 anteriorly, yellowish brown spot in middle posterior to dark tentorial pits; 

 small, sharp, chestnut brown dots of wedge-shaped pattern; several large, 

 indistinct dots lateral to posterior branches of frontal sutures and apex 

 of coronal suture. 



Dark dorsal areas with relatively large, dark, tubercles with round apex; 

 tubercles become smaller at boundary of the lighter area, pointed or form 

 thin spinules with a thick base; a transverse stripe of these and smaller, 

 needle-shaped spinules in rows of 2—3 in the posterior part divides the dark 

 from the light, smooth area. Lateral surface tubercles wider and lower, 

 almost adjoining; ventral surface with reticulate pattern except for a smooth, 

 light occipital area; cells forming ridges near lateral or anterior margin; 

 ridges in some places serrated with one or several spinules. Gula oblong, 

 chestnut brown, irregularly triangular, with curved sides, rounded posterior 

 corner, and finely tuberculate surface (Figure 190, B). 



Intermediate and median anterior-margin setae blackish brown, 

 moderately long, the latter smaller than the former; lateral seta light, 

 moderately long, slightly curved; anterior frontal seta brown, slightly 

 larger; middle frontal seta thinner, shorter, light brown; both directed 

 inward; posterior frontal seta brown, thick, moderately long. Secondary 

 setae brownish, 18—20 small, short to moderately long setae on sides 

 of anterior part: 11—12 small, light setae in posterior part along sutures. 



142 



