CLASS MAMMALIA. 65
principal food is aquatic vegetables, of which it only takes
what can well be spared. Occasionally, when it is abundant
and the weather severe, it does mischief among osier beds;
but the injury inflicted on the farmer is so small as hardly
to be worth consideration.
Arvicola agrestis, Linn. Common, or Short-Tailed, Field
Vole.
This Vole abounds sometimes to such an extent as to
entirely destroy the herbage. From the quantity of food
consumed by it, it is easy to conceive the devastation it may
cause when existing in large numbers. Not satisfied with
herbage only, Voles, according to Bell {Brit. Quadrupeds,
p. 325), were known, many years since, to destroy the planta-
tion of young oaks in the New Forest and in the Forest of Dean.
Some years ago, I recorded (Zool, 1881, p. 461) the weight of
food, amounting to six drachms (apothecaries weight) of clover,
consumed during the space of four-and-twenty hours, by a
specimen I had in confinement.
Its insatiable appetite compels it to be abroad at all
seasons of the year and all hours of the day ; but I have
noticed those in captivity to be more active towards and
during the evening. They appear rather stupid, and I never
succeeded in making them very tame.
Bell says Arvicola agrestis may always be distinguished
by the character of its second upper molar, which has five
cemental spaces, whereas the tooth in Arvicola arvalis (not yet
found in Great Britain), as in all the other European Voles,
presents four spaces.
The nest is usually placed among the roots of grass,
sometimes under fallen timber. The young are from four to
six in number, and there are generally three or four broods
in year. Weasels, Owls, and Kestrels, are their greatest
6