107 



Prothoracic horn dark brown (Figure 172), shorter, wider at the base 

 than in the form preceding, with light apex, and small spinules basally, 

 almost to the middle. Sternite barely visible, consisting of 2 fused, 

 triangular, indistinct, brownish areas. 



Legs uniformly brown. Coxae with large dots basally. Anterior 

 surface of fore coxa with spinules only in the middle, these spinules lighter 

 and smaller than in B.bellicosa; large spinules situated singly, basally, 

 and ventrally to the anterior primary spinules. Posterior primary seta 

 and ventral primary setae of femur equally spaced at base (Figure 173, A). 



Postsegmental gills present on segments 2—4, presegmental gills dorsally 

 on segment 2, segment 3, in contrast to B.bellicosa, without gills. 



"Ventral elliptical areas on segments 2—7 small, distinct. 



Tergite of segment 9 light brown, with large, pale dots near anterior 

 margin; setae chestnut brown, medioanal setae and the anterior-angle setae 

 moderately long; fewer secondary setae than in B.bellicosa. 



Sclerite "b" of anal legs light brownish, with reddish brown spinules 

 dorsally, spinules larger near the inner margin; lateral and ventral areas 

 with scale-shaped, thin spinules; distodoi sal setae dark reddish brown, 

 lateral setae thinner and markedly shorter than the other two; median 

 margin with a brown, thin, moderately long seta; setae absent on the surface 

 among the spinules; ventral seta brown, thick, moderately long. Sclerite 

 "c" yellowish, with brownish spinules and dark reddish brown outer margin; 

 basal seta short, yellov/ish brown. Claw and its setae as in B.bellicosa. 



Case 11— 15 mm long (Figure 174), made of smaller and more smoothly 

 arranged sand grains than in B, b e 11 i c o s a, conical, strongly curved, with 

 coarser grains laterally; anterior opening markedly truncate, with dorsal 

 hood; posterior opening covered with dark brown membrane with a large 

 central hole. 



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

 on stones overgrown with green algae and diatoms. 



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



4. Genus Baicalinella Martynov 



Full-grown larva. Medium-sized, 9— 11.5 mm. Sclerites of head dorsally 

 and ventrally with dense spinules, except for the occipital stripe and the dots; 

 secondary setae absent. Gula broad, narrower posteriorly, with curved 

 sides. Thoracic sclerites with covering spinules; row of large spines on 

 anterior margin of pronotum absent. Prothorax with horn. Gills absent, 

 or rudimentary if present, on abdominal segment 2. Tergite of abdominal 

 segment 9 pale whitish, with 2—3 secondary setae. 



Case made of coarse sand grains, conical, strongly curved, crudely made. 



Mode of life and habitats. Open areas of the shore, usually at 

 a depth of 5— 10 m; single specimens occur deeper. 



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



1. Baicalinella foliata Martynov 



Bebutova, 1941:99—100, Figures 67—81, - Lepneva, 1964:669-676, 

 Figures 4, 8, 12, 14, 18, 22, 



130 



