these larvae sometimes cover the stones completely. The larvae of 

 Baicalodes ovalis live at greater depths, preferring small stone 

 screes; they are present in large numbers only in the 8— 10m zone; the 

 larvae of Baicalinella foliata prefer a sandy bottom; Apatania 

 baicalensis prefers a sand-clay bottom in the 2—1 m zone, rarely in the 

 10— 30 m zone; in all these biotopes and depths the larvae find abundant and 

 very nutritive food in the overgrowths of algae, fungi and bacteria. 



The pupae of Thamastes dipterus climb in spring from the water 

 through cracks in the ice before all other species; adults of this species do 

 not fly but run on the water and on ice, concentrating sometimes on stones 

 on the shore close to the water. Other species fly in large numbers, but 

 scatter higher and more widely in the coastal zone, covering the branches 

 of trees to a height of 10m; the flight of these species is described below 

 (p. 167). 



The endemic forms of Lake Baikal predominate in open and wide bays; 

 however, together with this fauna appear other common species. For 

 example, in the Anga inlet, the entrance of which is 1.3 km wide, occur 

 Thamastes d i pt e ru s, species of Baicalina (B. thamastoides, 

 B. bellicosa, B. spinosa), Baicalodes ovalis and Baicalinella 

 foliata; in various biotopes occur also the common Palearctic species 

 Agrypnia obsoleta and Molanna palpata. In the Posol'skoe salina, 

 which is an inlet separated from the sea by a sand bar, the only Baikal 

 element (represented by isolated specimens) is Apatania baicalensis; 

 the main faunas of caddis flies of the inlet consist of common Palearctic 

 and Siberian species, including Nemotaulius punctatolineatus 

 and Molanna palpata. In the Kurkut inlet of the Maloe More (lesser sea) 

 the only Baikal species are isolated specimens of Baicalinella foliata; 

 the lacustrine forms of Siberia are represented by the species Agrypnia 

 ob s o 1 e t a, Ph r y ga ne a s t r i a t a, P h. r o t u nd at a, Molanna pal- 

 pata, Leptocerus a nn ul i c o r n i s, M y s t a c i d e s longicornis, 

 Oecetis ochracea and Limnophilus nigriceps (Bebutova, 

 1941:84-88; Levanidova, 1946). 



The characteristic fauna of Trichoptera of the Aral Sea (salinity 10.1 %o) 

 consists of two species which tolerate a high salinity, Agrypnetes 

 crassicornis and Oecetis intima, which are widely distributed in 

 this lake. O. intima occurs also in the Mertvyi Kultuk Bay of the Caspian 

 Sea (Bening, 1934:194; 1937:172; 1940:95-96; Khusainova, 1959:10). 



Ponds. Trichoptera are absent in young ponds as well as in old 

 "decaying"* ponds, especially in ponds covered with L emna with hydrogen 

 sulfide near the bottom. Isolated specimens, or small numbers of species 

 found in lakes, occur in ponds which are at least partly ventilated by 

 photosynthesis or by the inflow of fresh water from a source; some of these 

 forms are very abundant. The ecological characteristics of caddis flies 

 128 of ponds are determined by the water source and the regime of the ponds. 

 In small trout ponds with a solid bottom on the fishery farm "Ropsha" 

 (Leningrad Region), which are fed by cold water from the large limnocren 

 Iordan', occur the lithophilic larvae of Apatania sp., Potamophylax 

 stellatus and Chaetopteryx sp., which occur also in the limnocren. 



In "moribund" ponds, according to the classification of Lukin (1954:96—101). 



120 



