IX.] 



WESTERN DIVISION. 



343 



Holarctic, the typical Z. hudsonianus dating from the Plistocene 

 epoch. A distinctive feature of the western Holarctic region is 

 the absence of true porcupines (Hystrix), their place being taken 

 by the Canadian porcupine (Erethizon], which belongs to the same 

 sub-family as the South American porcupines, although distin- 

 guished, among other characters, by its short and non-prehensile 

 tail. It is a native of the wooded portions of Canada and the 

 United States, and its remains have been discovered in a cave in 

 Pennsylvania. 



FIG. 69. ROCKY MOUNTAIN GOAT (Haploceros montamis] 



Among the ungulates, the remarkable animal known as the 

 Rocky Mountain goat, which alone represents the genus Haplo- 

 ceros, and differs from all other ruminants by the extreme shortness 

 of the cannon-bone in both the front and hind limbs, is exclusively 

 an inhabitant of the western Holarctic region. The same is now 



