Below the outflow appears a group of small species characteristic of the 

 Biya, e. g., Hydroptilidae (St a ct ob i e 11a biramosa, Padunia 

 adelungi and P.lepnevae) and Psychomyiidae (P sy c h omy i e 1 1 a 

 compos it a and P. minima); the larvae of these tachypotamobionts live 

 on pebbles; the adults appear in large numbers concentrating on stones, 

 shrubs and trees; they land on vessels and rafts. The tachypotamobionts 

 of the Biy a River include the larvae of Stenopsyche griseipennis 

 which are absent in the tributaries of Lake Teletskoe and the lower 

 reaches of the Biya. This species occurs in small numbers on the western 

 boundary of its range. In the Biya River occur the following species, which 

 are also characteristic of larger rivers in the plains: Diploglossa 

 nylanderi, Agapetus sibiricus, Hydropsyche kozhantshi- 

 kovi. In the lower reaches of the river, near Biisk occurs also 

 Hydropsyche ornatula; Leptocerus annulicornis was found 

 near the banks of the river. 



The fauna of Trichoptera in the foothills of the Western Sayan, in the 

 rivers of the Oya system (Tanzibei, Malyi Kebezh and Bol'shoi Kebezh) 

 has a similar character. In the Eastern Sayan, a similar fauna occurs in 

 the Mana River. In the small rivers of the Sayans occur the following 

 stream elements: Rhyacophila impar and Mystrophora altaica; 

 in the Mana River occur Rhyacophila sibirica and Rh. lata.* The 

 larvae of Stenopsyche griseipennis were found in large numbers 

 in the Tanzibei stream but they disappeared higher along the profile. They 

 live on small stones or large pebbles. In the Malyi Kebezh and Bol'shoi 

 Kebezh rivers, and in the Mana River, occur Arctopsyche ladogensis 

 and Hydropsyche nevae; of the species characteristic of larger rivers, 

 there is Hydropsyche ornatula in the lower reaches of the Bol'shoi 

 Kebezh; in the lower reaches of the Mana River occurs Macronema 

 radiatum and B r a c hy c e nt r u s subnubilus (Lepneva, 1948b:96; 

 1949:256-257). 



In Ciscaucasia, the foothill rivulets with rapids include the Psekups 

 River, which is a tributary of the Kuban. Larvae of Rhyacophila sp. 

 (which belong to the stream fauna) occur at the banks of this brook in some 

 places. The larvae of Psychomyia pus ill a (to 400 specimens per m ), 

 Che umat op sy c he lepida and Hydropsyche sp. are typical 

 elements of the bottom fauna of the brook; Hydroptila sp. and Agray- 

 lea pallidula are common in turbulent water. 



Large and small rivers of the plains. The larvae of caddis 

 flies are a constant, sometimes predominating, element of the bottom fauna of 

 the large rivers of the Siberian and European plains; these faunas are 

 distinguished by their uniform taxonomic and ecological composition; they 

 have the same ecological appearance for hundreds of kilometers in these 

 large rivers. 

 120 Stream elements are usually absent in these rivers; they occur only 

 sporadically in tributaries with a regime like that of streams. The fauna 

 of some Siberian and north European rivers include the species Arcto- 

 psyche ladogensis and Hydropsyche n e va e, which are 

 characteristic of the rivers of the southern Siberian foothills. The main 

 faunas of these rivers, however, are potamobionts which are restricted to 



* Wrongly recorded as Rh. manuleata by Lepneva (1948b:68 and 1949:256). 



II 



