Mode of life and habitats. Slow brooks with abundant fallen 

 leaves on bottom. 



Distribution. Western part of the Eui-opean USSR, Caucasus, Ci'imea. 

 In addition, Europe. 



4. Genus Hales us Stephens 



Full-grown larva. Length 17— 2 6 mm. Head brownish, with large, 

 distinct, chestnut bi'own dots; light areas of head little differentiated. 

 Gi'oove in antejnor third of pi'onotum dark in middle. Mesonotum lighter 

 than pronotum. Anterior median tergites of metathorax, long, triangular, 

 ,280 not fused. Fore trochanters with a row of hairlike chaetoids curved 



distally on entire distal pai/t fi'om suture; mid- and hind tibiae and tarsi 

 with vent]'al I'ows of spinules. 



Dorsal process of abdominal segment 1 wide, blunt. Presegmental gills 

 present on abdominal segment 2 . 



Case made of detritus, 22—35 mm long, with snaooth surface except if 

 particles of ti-ees ai-e used; long ]-ods sometimes present at ends, increasing 

 length to 40—45 mm. 

 281 Mode of life and habitats. Brooks and rivulets with abundant 

 detritus; open shore of lakes. 



Distribution. Northern, no i-thwestern, and central pai'ts of the 

 European USSR, Caucasus, Siberia (rare), Sakhalin. In addition, Europe, 

 Iran, Japan. 



Key to Species 

 Full-grown larva 



1 (2). Medium sized, 17.5— 21.0 mm long; groove in anterioi' third of pro- 



notum dark, dark brown in middle; abdominal segment 2 usually 

 without lateral presegmental gills; case smooth, made of small 

 pieces of detritus, sometimes with a small rod projecting posterior- 

 ly. Rare; isolated records from westei-n border of the USSR and 

 northern Caucasus 3. H. digitatus Schrk. (p. 360) 



2 (l). Larger, 2 0— 2 6 mm; groove in anterior third of pronotum slightly 



dark in middle; abdominal segment 2 with lateral presegmental 

 gills; case often smooth, sometimes made of coarse tree detritus, 

 with rough surface and rods projecting beyond ends. Common in 

 large areas of European USSR. 



3 (4). Darker than H. i n t e r pu n c t a t u s; posterior margin of pronotum 



with short, black median stripe and a long lateral stripe extending 

 in a thin end before median stripe almost to suture; anterior 



median sclerites of metathorax brown, distinct 



2. H. tesselatus Ramb. (p. 358) 



4 (3). Lighter; black lateral stripe at posterior margin of pronotum 



extending above median stripe only to middle of half of sclerite; 



anterior median sclei'ites of metathorax pale, indistinct 



1. H. interpunctatus Zett. (p. 353) 



352 



