Case straight, slightly tapering posteriorly, sometimes slightly curved, 

 and with slightly flattened ventral surface made of sand, small stones, sand 

 and detritus, or detritus only, usually coarse particles of detritus, sonne- 

 times with long rods. 



Mode of life and habitats. In rapid and slow streams; some 

 species inhabit surf zone of lakes; the small larvae of Enoicyla live 

 outside water. 



Distribution. Throughout the USSR. In addition, Europe, Africa 

 (northern coast), Iran, Pakistan, China, Japan, North America. 



Key to Genera 

 Full-grown larva 



1 (4). Case made entirely of sand grains or small stones, sometim.es 



with particles of detritus at posterior end. 



2 (3). Case smooth, made of sand grains, slightly flattened dorso- 



ventrally 1. Potamophylax Wall. (p. 314) 



3 (2). Case walls not very smooth, made of sand grains, anterior part 



often with small stones 6, Micropterna Stein (p. 367) 



4 (1). Case made of detritus or detritus and sand. 



5 (10). Dorsal side of head and thoracic tergites with continuous punctate 



pattern; case straight. 



6 (9). Abdominal segment 2 with presegmental gills. 



7 (8). Case smooth; detritus particles of varying size, sometimes in- 



cluding long, rodlike pieces projecting posteriorly 



4. Halesus Steph. (p. 352) 



8 (7). Case smooth; detritus particles in form of thin plates with closely 



fitting margins 3. Stenophylax Kol. (p. 35 O) 



9 (6). Abdominal segment 2 without presegmental gills 



2. Hydatophylax Wall. (p. 337) 



10 (5). Pattern on dorsal side of head and thoracic tergites with light, 



longitudinal, median stripe; case slightly curved 



5, Anisogamodes Mart. (p. 362) 



1. Genus Po t am o p hy 1 ax Wallengren 



Full-grown larva. Length 17 — 25 mm. Head uniformly dark, reddish 

 brown or yellowish, rarely with stripes and spots on light background; 

 groove in anterior third usually dark. Anterior-median tergites of meta- 

 thorax transverse, contiguous, but not fused. Abdominal segment 1 without 

 dorsal process. Abdominal segment 2 with dorsal and ventral presegmental 

 gills but sometimes without pleural presegmental gills. Abdominal seg- 

 ment 9 with numerous, secondary setae. 



Case made of sand grains, rarely sand grains and detritus or only 

 detritus. 



314 



