large and small hooks as follows:- 111:3+3; IV: 3+1; V: (anteriorly) 

 4 + 1, (posteriorly) 9-10; VI:3+2; Vll:4 + 2. 



Gills on segments 2—3, as in the larva. Lateral line from end of 

 segment 5 to 8, consisting of long, thin, delicate, grayish white setae. 



Case slightly shorter than in the larva, to 10 mm long; posterior 

 opening as in the larva. 



Mode of life and habitats. On stones among vegetation; 

 microphytophagous; open shore of Lake Baikal. 



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



2. Genus Baicalodes Martynov 



Full-grown larva. Slightly larger than Thanaastes, usually 

 14.0— 14.5mm. As in Thamastes and in contrast to Baicalina, 

 sclerites of head (except gula), pronotum, and mesonotum mainly smooth, 

 without spinules. Small, light, secondary setae more numerous than in 

 Thamastes. Gula larger than in Thamastes. 



Horn absent. Gills on abdominal segments 2—3. 



Case 15— 20 mm long, made of large sand grains, curved, tapering 

 posteriorly, with rough surface. 



Mode of life and habitats. Open shore of Lake Baikal. 



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



1. Baicalodes ovalis Martynov 



Bebutova, 1941:97—99, Plate 4, Figures 51—60.— Levanidova (Bebutova), 

 1945, Dissertation. - Lepneva, 1964:669-676, Figures 2, 6, 10, 16, 20. 



Full-grown larva. Length 12.0— 14.5 mm.-* Head (Figure 151, A) mainly 

 chestnut brown; area anterior to the eye, spot of tentorial pit, and small 

 areas lateral to the gular suture reddish brown; dots light. Wedge-shaped 

 pattern on frontoclypeus pale, dots of posterior row more distinct; large 

 light dots along the epicranial suture, behind the eye, and ventrally near 

 the occipital foramen. Gula reddish brown, its posterior angle slightly 

 lighter, pointed; gula and area lateral to it densely covered with small 

 spinules (Figure 151, b). 



Median anterior -margin seta yellowish, thick; intermediate seta brown, 

 long, both setae slightly flattened, lateral seta short, light. Anterior frontal 

 seta the same, middle seta small, light, spine-shaped, posterior seta thin, long, 

 brown; 2 — 3 small, secondary light setae in the area of the anterior -margin 

 setae; 5—6 such, light, small setae posteriorly along the suture. Seta 7 

 short, brown; seta 10 small, spine -shaped, light; setae 9 and 14 brown, long, 

 slightly thickened; seta 11 thin, some distance from 9, near the posterior 

 margin and the light ocular area; seta 12 thicker, brownish, slightly longer; 



The 1st figure refers to large denticles; the 2nd, to small denticles. 



Measurements from material in the Zoological Institute of the USSR Academy of Sciences. Published 



measurements are larger, 16— 18mm (Bebutova, 1941:97). 



Ill 



