OCT., 1900.] SUMMAKY OF FAUNAL DISTRICTS. l7 



the Pacific coast. The occurrence at Skagway of iiiummals of the 

 interior, such as Mlwotus m'ordax,^ Evotomys dmcwnl, and Peromyscua 

 or^eas, seems to show an approach to the condition farther north where 

 the coast and interior forms are practically the same. The Canadian 

 zone of the Lynn Canal district gives way to the Hudsonian and 

 Arctic-Alpine in the White Pass district. The character of this dis- 

 trict is essentially the same as that of other mountain regions in 

 western North America. This is well indicated by the fact that its 

 mammals include the hoary marmot {Arctomys caligatm), the Alaska 

 pika {Ochotona coUaris), and the mountain goat {Oreamnos mo7itanm)^ 

 and its birds the ptarmigan {Lagopiis Imourus and Z. rupestris), the 

 pipit (Anthuspensilvamcits), and the rosy finch (Leucostccte t. littoraUH). 

 The Canadian Yukon district from Bennett to Fort Selkirk merely 

 represents the extent to which our route entered the extreme northern 

 part of the Canadian zone; that is, its limits are those of the section 

 that our route made across the end of a narrow tongue which extends 

 northward from the great areas occupied by the Canadian zone farther 

 south. Owing to its being so near the border of the Hudsonian zone, 

 its character is not purely Canadian, but the presence of such forms 

 as chipmunks {Eutamias) and white-footed mice {Peromyscus) among 

 manmials, night hawks {CJiordeiles) among birds, and lodgepole pines 

 {Plnus murrayana) among trees, makes it evident that the Canadian 

 element is very strong. The Hudsonian Yukon district represents the 

 complete section which the Yukon River makes through the great 

 northern forest belt of the Hudsonian zone. This belt corresponds to 

 the Alaskan-Canadian district outlined by jTelson. It is bounded on 

 the south by the Canadian zone and the extreme northern limit of 

 southern forms, and on the north by the treeless tundra. On the west 

 it probably reaches and includes the coast from Kadiak to Lynn Canal; 

 on the east its limits are unknown. The Alaska Tundra district defines 

 itself. Its character is the combined result of latitude and rigorous 

 coast clunate. Our experience in this treeless district was limited 

 to St. Michael Island and the ninety miles between Andraefski and the 

 mouth of the Yukon. The animals of this region are not all abso- 

 lutely confined to it, many of them ranging some distance into the 

 forest belt. Small mammals, such as the Nelson vole {Mlcrotm ope- 

 rarim), occupy so-called ' islands '—local spots oft'ering what are prac- 

 tically tundra conditions— as far within the forest belt as Circle. 



'The case of Microtas mordax at the head of Lynn Canal is particularly interesting, 

 since a closely related form, M. macruriis, has been found at Glacier Bay on the 

 north side of the mouth of the canal and also at Juneau on the south side, and 

 would therefore be expected at Skagway, which is halfway between. Assuming 

 that 7namirus has been dispersed from tlie south northward on the coast, it seems 

 that it did not reach Glacier Bay by way of the present mainland, otherwise it would 

 be fomid at Skagway. M. mordax doubtless reached Skagway from the interior. 

 4494— No. 19 2 



