GEOGRAPHICAL DISTRIBUTION 415 



comparative narrowness of the Behring Straits, across which 

 there was a land-bridge at no very remote period, geologically 

 speaking. At one time, too, Europe and North America were 

 connected by land occupying the North Atlantic, and the sea 

 between Britain and Greenland is still comparatively shallow. 

 It may be objected that even if such unions once existed the 

 rigour of the northern climate would prevent land animals from 

 migrating across them; but we know that there have been many 

 changes in climate during the past history of the globe, and that 

 for part of the time when these land-bridges existed a much 

 higher temperature prevailed in the areas they occupied than is 

 now the case. Besides which, the objection, even if valid, would 

 not apply to Arctic forms; and, further, many animals which we 

 now associate with the warmer parts of the earth are able to 

 endure a larger amount of cold than is sometimes supposed. It 

 may be added that the resemblances between the faunas of the 

 Palsearctic Region and the northern part of North America are 

 so striking that many writers associate these together under the 

 name of the Holarctic Region. This fact is mentioned because 

 in dealing with certain forms it will be convenient to speak of 

 them as being "holarctic '. 



Palcearctic Maitinials {Mamtnalid). — Among Insect-eating 

 Mammals {Insectivora) our common Mole {Talpa Et(,ropad) and 

 related species of the same genus are confined to this region, as 

 also are the Desmans i^Myogale), while Hedgehogs {Erinaceidce) 

 are very characteristic, though not peculiar. Of the Flesh-Eaters 

 {Carnivord) very few are entirely limited to the region, the most 

 notable being the Raccoon-Dog [N'yctereuies, fig. 1287) of north- 

 east Asia, and the Common Badger [Meles taxus) with some of 

 its immediate allies. It should be stated, however, that a number 

 of Carnivores are purely holarctic, e.g. the Polar Bear {Ursus 

 maritiimis), the Glutton {Gulo luscus), Lynxes, and Arctic Foxes; 

 while some others are very characteristic, e.g. Wolves, Bears (other 

 than the Polar species). Martens, and Weasels. Some aquatic Car- 

 nivores are entirely holarctic, such as the Sea Otter {Latax httris), 

 the Greenland Seal [Phoca Grcenlandica), the Walrus {Trichechus 

 rosmarus), and the Greenland Whale {Balisna mysticetus). 



The Palsearctic region is comparatively rich in Hoofed 

 Mammals {Ungtdata) native to no other part of the world. 

 Among these are conspicuous typical Oxen {Bos), Goats {Caprd), 



