The runs are a conspicuous feature of the islands, among the heather and the rough vegetation of the fields and hillsides, running along the surface and at intervals entering tunnels about two and a quarter inches in diameter--just sufficient to clear the spread of the Vole's whiskers. Their nesting places, like those of the Mole, are under small mounds connected with a network of runs. The nest itself is made of grass and roots in a rounded chamber, where at intervals during the spring and summer several litters, varying from three to six, are produced. Before they are three weeks old they are capable of independent existence, but for a time are still guarded by the mother. The Orkney Vole appears to be specially fond of the roots of Heath Rush (_Juncus squarrosus_), but also feeds on grass and the crops in cultivated fields to which they can gain access. Mr. Millais found that in cold weather his captive Voles became inactive. It has many enemies to hold its increase in check, for every bird and beast large enough to capture it will eat it readily. *Bank Vole* (_Evotomys glareolus_, Schreber). There can be little doubt that in many places the Bank Vole has been mistaken for a bright variation of the Field Vole. Its habits are much the same, except that it haunts the hedgerow and wooded country rather than the open fields. As to the differences between the two species, the Bank Vole's head and body measurement is only three and three-quarter inches against four inches in the Field Vole, but its tail is actually (not merely proportionately) longer, being nearly half the length of head and body, and ends in a pencil of hairs. The ears and feet are proportionately larger, the former also being more oval than round. It further differs from the other Voles in the fact that the molar teeth become rooted in the jaws of the adults. The fur of the upper parts is a bright chestnut-red or Vandyke brown, excepting the hairy tail, which is black above. The under parts, including the lower side of the tail, are whitish varying to yellowish or even buff. The redder tint causes this species frequently to be styled the Red Vole. It has pink lips, and grey feet. Whiskers about an inch long. Black and albino varieties have been recorded.