16 NORTH AMERICAN FAUNA. [no 19- 



arctica^ Riihun cJutmiam'xynis^ Iii(l>iis (irctlGus^ Betida nana, Alnus 

 sinuata. CIt<( nuvcii^tux jn'ocairiheus, and Tnsnlago frigida. 



SUSEVIAKY OF FAUXAI. DISTRICTS. 



All the country horo, consitlorcd is in the boreal zones, the Tundra 

 district and a small part of the White Pass district belon«^ing- to the 

 Arctic subdivison, and the Yukon Valley principally to the Hud- 

 sonian, thoutj;-h it has also a well-marked Canadian section. Birds 

 are comparatively rare in all the interior region, and it is difficult to 

 determine the exact range of many species. Some were seen but 

 once or twice; others appeared sporadically at rather long intervals; 

 while still others that are known from the region were not seen at all; 

 so it is hardly safe, in making generalizations, to ridy too much on 

 the ranges obserxed b}- us. The distribution of trees and shrubby 

 plants and of man}' of the manmials, however, could be determined 

 with much greater accuracy and constitute reliable guides in fixing 

 the limits of the districts. These districts are in general the same 

 as those recognized by Nelson, but with more definite and somewhat 

 modified limits. Names slightly different from those he used are 

 adopted here in order to agree with the commonly accepted names 

 of the primary zones of North America. Thus the part of his 'Alas- 

 kan-Canadian' district here considered is called the 'Hudsonian 

 Yukon ' district, since it lies entirely within the transcontinental Hud- 

 sonian zone. Owing to fluviatile conditions, the boundaries of the 

 Yukon districts doubtless do not agree in latitude with those which 

 might be made away from the rivers. 



The zones which we successivel}^ traversed in going from Skagway 

 to St. Michael via White Pass and the Yukon are: (1) Canadian; (2) 

 Hudsonian; (3) Arctic- Alpine; (4) Canadian; (5) Hudsonian, and (6) 

 Arctic. The Lynn Canal district is in the Canadian zone, but it has 

 some slight peculiarities such as are to be expected in a coast district. 

 Though it does not have the Hudsonian animals of the northern coast, 

 it lacks several of the typical Canadian forms of the coast farther 

 south. ^ It is really near the northern limit of the Canadian zone on 



^The coast of Alaska south of the peninsula, or what has been known as the 'Sit- 

 kan district,' may be easily divided into two districts corresponding to the Canadian 

 and Hudsonian zones. Lynn Canal is situated near the boundary between these 

 districts. Among Canadian mammals which have their center of abundance in the 

 restricted Sitkan district on the coaat south of Lynn Canal are: OdocoUeus sitkensis, 

 Sciurus vancouverensis, Peromyscus ^nacrorhinus, Erotomys urangdi, Microtus maatii'us, 

 Synaptomys wrangeli, Zapus mltator, and Myotis alascerms. Among the Hudsonian 

 forms found on the coast only north of Lynn Canal are: Eangifer sp.. Oris dalli, 

 Sciunts hndsonicus, Spermophihtx r. plmufi, Zapus h. alascensis, Ochotonn coUaris, and 

 Myotis hiclfugm. Among trees which find their northern limit in the vicinity of 

 Lynn Canal are: Thuja plkaia, Ahies lasiocarpa, and Phnis murrayana. The northern 

 district from Lynn Canal to Kadiak is so similar to the great interior Hudsonian 

 region that it hardly merits recognition as a distmct district, but it certainly should 

 not be included in the Sitkan district. 



