spot laterally, without spinules. Large setae dark, brownish; thin and small 



setae brown or light brown; medioanal and anterior-angle setae thicker 



than the others, the latter situated slightly inward, not at the margin but 



subapically and not in the outer angle; 2 other setae between the medioanal 



setae, one of them long, dark (shorter and thinner than the primary 



setae), the other moderately long, brownish, thin; 5 large setae at the margin 



between the anterior anal setae and the anterior -angle setae, including 



an intermediate and a lateral primary seta, 2 of them long, slightly shorter 



than the median setae; a thin, pinkish moderately long seta near the 



marginal setae, also a small seta lateral to the anterior- angle seta near 



the margin. 



Sclerite "b" of anal legs pale yellowish^ pinkish posteriorly, laterally and 

 ventrally, dorsally with pinkish brown spinules, larger spinules near the 

 anterior margin; lateral surface with scale- shaped, pectinate tubercles 

 instead of spinules; a median and a neighboring seta dorsally, long, thick, 

 black, the lateral seta reddish brown, thin, moderately long; distoventral 

 seta short, brown; median margin with thin , brownish, moderately long 

 seta. Sclerite "c" yellow, with scale-shaped, pectinate tubercles with wide, 

 reddish, dark brown outer margin; seta small, thin, brownish at the base. 



Claw brownish and finely spinulose at the base, smooth, reddish brown 

 and densely sclerotized apically; seta 1 situated on the median side, 

 short, light at the base; seta 2 light, moderately long, seta 6 short, both 

 situated near end of suture, seta 6 laterally, reddish brown; seta 3 smaller 

 than 2, situated on the inner side in the apical area, thick, brownish; baso- 

 ventral seta 7 and 8, situated close together at the margin and on the 

 membrane, both light and slightly curved at the end; seta 5 situated near 8, 

 small, light; seta 4 situated more median, small, light, slightly thicker. 



Case (Figure 163) 11— 15 mm long, made of coarse sand grains, roughly 

 constructed, its ventral surface sometimes smoother but with one or 

 several coarser grains among the more smoothly arranged grains; dorsal 

 surface forming a heap of coarse sand grains, always coarser and sometimes 

 with small stones laterally. Anterior end of case forming a large, convex, 

 dorsal hood, anterior opening directed downward, its margin level with 

 the ventral surface; posterior opening covered by a membrane with one 

 large or 2—3 smaller holes. Posterior membrane of pupal case with 3-4 

 openings. 



Mode of life and habitats. On stones, at a depth of 2—5 m, rarely 

 at 10 m, isolated specimens even deeper. 



Distribution. USSR: Lake Baikal. Not known outside USSR. 



2. Baicalina spinosa Martynov 



Bebutova, 1941:90—92.— Lepneva, 1964:669—676, Figure 21. 



Full-grown larva. Length 12— 16 mm. Sclerites of head (Figure 164, A) 

 tuberculate; dorsal spinules smaller or slightly different from those of the 

 preceding species, conical, blunt, or tapering to a small, light filament; no 

 spinules laterally behind the eye; groups of small, blunt spinules (not large 

 or sharp as in B. b e Hi c o s a) present only lateral to gula. Gula brown, 

 long, relatively narrow, more than twice as long as wide, smooth anteriorly, 

 with small spinules in the middle and posteriorly (Figure 164, B). 



12:^ 



