small, dark; no setae on the surface. Sclerite "c" wide, irregularly- 

 triangular, with reddish brown outer margin; basal seta small, light. 

 Claw light brown basally, dark reddish brown apically; seta 1 short, 

 seta 3 long, both brown; seta 2 situated dorsally above end of suture, 

 light, yellowish, long; seta 6 brown, small, situated lateral to seta 2, 

 near end of suture; seta 7 small, dark brown, situated ventrally; seta 8 

 slightly more apically near the margin on the membrane; seta 5 small, 

 situated laterally on the margin; seta 4 situated ventrally on the membrane. 



FIGURES 155 and 156. Baicalodes ovalisMart.: 



155 — dorsal sclerite of abdominal segment 9; 156 — case of larva, lateral 

 (A) and ventral (B). 



Case (Figure 156) 15— 20 mm. long, made of large coarse sand grains, with 

 rough surface, curved, tapering posteriorly, slightly flattened ventrally. 

 The flattening of the case is accentuated by coarse gravel grains, situated 

 closer to the ventral margin; while the case is being made, its posterior 

 end may remain attached for a long time; such long cases with narrow, 

 uninhabitable posterior end, a remnant of the preceding stage, may be 25—26 

 and even 30 mm long. The walls often contain small mollusk shells in 

 addition to sand grains. Anterior end of case truncate; posterior end 

 covered by a brown membrane with scattered, large, sand grains and an 

 asymmetrical round hole; periphery of membrane sometimes with several 

 small holes also. 



Mode of life and habitats. Usually on sandy, stony places and 

 sand on the open and overgrown shore, especially among Draparnaldia, 

 deeper than other species, 5 to 15— 20 m; rarely found above 5 m and 

 below 2 m. 



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



3. Genus Baicalina Martynov 



Full-grown larva. Relatively large, 10—16 mm. Head, thorax, legs, and 

 abdomen with dense cover of small spinules. Gula oblong, tapering 

 posteriorly, much longer than wide, with curved sides. Frontoclypeus without 



116 



