Two or three species of vole (Arvicola) have been detected, and porcupines are common.
The second and larger species is the water-rat, or "watervole," which belongs to a second section of the genus, and is commonly known as Microtus (Arvicola) amphibius, although some writers employ the inappropriate specific name terrestris.
The snow-mouse (Arvicola nivalis) is confined to the alpine and snow regions, and is abundant at these levels throughout the whole chain of the Alps.
Minutus), four voles (Arvicola amphibius, A.
Schistocolor), the beaver, variable hare, wild boar, roebuck, stag, reindeer, elk and Phoca annelata of Lake Baikal - all these are common alike to Europe and to Siberia; while the bear, musk-deer (Moschus moschi- f erus), ermine, sable, pouched marmot or souslik (Spermophilus eversmani), Arvicola obscures and Lagomys hyperboraeus, distributed over Siberia, may be considered as belonging to the arctic fauna.