CULTURE OF CIRCUMTOL-VR ZONE — BOGORAS 473 



Tlie same refers to tlie birds ot passage. Muinberless (locks of 

 waterfowl of all species come to the north even from the hemi- 

 sphere across the Equator. Accorilin»^ to the conditions of the 

 climate, they may spend only four months in the north against 

 eight months in the south. Nevertheless the north is their usual 

 breeding place. Here they have their mating and nesting periods, 

 and the short summer time suliices even" for the growing up of the 

 young wiu), after that, depart along with the older generation to- 

 ward the south, wiiich is wholly unknown to them. To be sure, all 

 the northern land is covered with bogs and watercourses and there 

 is room enough for the breeding of the young. Nevertheless this 

 instinct of migration is very remarkable in the birds of passage. 

 One must presume that the migration of birds, with all instincts and 

 exertions referring thereto, is not exceedingly ancient. It could have 

 originated only in the Quaternary period when the configuration of 

 the mountains and the larger areas of land, also the distinctions of 

 the climates, already existed on tlie same plan as at present. In the 

 Tertiary period the birds of that time probably had no need to 

 migrate northward. The climate of the terrestrial globe was more 

 uniform, and especially in the north it was moderate and even warm. 



1. Most abundant of all .sections of animal life in the north is the 

 class of fishes. Sweetwater fishes also abound in the north. Such 

 are for instance the pike and the burbot. Burbot are caught in such 

 masses on the Kolyma and the Indighirka Rivers in the time of early 

 spring that the burbot livers cut out and frozen together form big 

 loads carried across the country with dog teams and pack horses. I 

 have seen caravans of pack horses each carrying frozen burbot liver in 

 two rectangular blocks of 50 kilograms. But maritime species, namely, 

 the salmon, are still more abundant. The migratory salmon of the 

 north may be divided into two large groups: Salmon of the genus 

 Coregonus belong to the Polar Ocean, and enter the rivers such as 

 the Kolyma, the Indighirka, the Yana, the Lena, the Yenissei, the 

 Obi. Salmon of the genus Oncorrhyncus belong to the North Pa- 

 cific Ocean and enter the rivers beginning from the Anadyr down 

 to the Anmr. It is curious to note that Kol3'ma and Anadyr, the 

 two great rivers of the northeast, which belong to the same ethnical 

 and cultuial area and the sources and headwaters of which meet 

 together in the mountains, have fishes of essentially dilTorent genera. 

 Kolyma has Coregonus species entering from the ocean, and some 

 Sweetwater species of Oncorr/n/iuw^. Anadyr, on the other hand, 

 has Oncorrhyncus entering from the ocean and some species of Core- 

 gonus of the Sweetwater branch. The species of Coregonus have 

 white flesh, those of Om-orrhyn< us, pink fiesli. Both groups in the 

 whole period of spawning do not care for any food and even do not 



