24 Merriam Geographic Distribution of Life. 



The Boreal Region is made up of two principal divisions, both 

 circumpolar : (1) An Arriic dirixinn. above the limit of tree 

 growth; and (2) A Boreal Qomferous Forest dir 1*1011. 



Arctic Ma/m/mals. 



(Found above the limit of trees and all circumpolar.) 

 A. Exclusively Arctic. 



Eskimo Homo 



Polar bear Thalarctos maritimus 



Barren ground bear Ursus richardsoni 



Musk ox Ovibos moschatus 



Barren ground caribou Rangifer grosnlandicus 



Arctic fox Vulpes lagopus 



Arctic hare Lepus glacialis 



Lemming Myodes obensis 



Lemming Cuniculm torquatus 



Arctic red-backed mouse Evotomys rutilus 



Parry's spermophile SpermopJiilns cinpctra 



B. Common to Arctic and Hudsonian. 



Wolverine Gulo luscus 



Gray wolf Canis griseus 



Ermine Putorius erminea 



The Boreal Coniferous Forest division may be subdivided into at 

 least two transcontinental zones : (a) Hudsonian, and (6) Cana- 

 dian ; and a third or ' Timberline Zone ' may be differentiated 

 from the Hudsonian proper. In speaking of the divisions of the 

 Boreal Region on high mountains it is customary to add the word 

 . alpine to the name of the division ; thus, Arctie-alpine, Hudson-id n- 

 alpine, and so on. 



Mammals of the Boreal Zone. 



(The letter a indicates that the species is known only from mountains, or 

 is an alpine form.) 



Cervus canadensis Sciurus fremonti 



Rangifer caribou cnogoilonensis (a) 



Alee americanus hudsonicue 



Mazama montana californicus (a) 



Ovis canadensis vancouverensis 



dalli richardsoni 



Sciuroptenifi volans sahuinus douglassi 



