Arvicola. mammalia. FERA. 23 
The dormouse is about the size of the common mouse, but fuller ; the tail 
is about 2^ inches in length, covered thickly with long hair. Eats its food 
erect. During winter it subsists on the store of nuts which it had prepared 
in autumn, and in very cold weather it becomes torpid. 
Gen. XXI. ARVICOLA, Vole. — N o subsidiary incisors. 
Roots of the grinders simple ; there are three on each side 
on both jaws. Tail round and hairy, and about half the 
length of the body. — The species of this genus differ from 
the true mice, with which the older authors confounded 
them, by the superior size of the head, the shortness of the 
tail, and the coarseness of the fur. 
34. A. aquatica. Water Vole. — Body 7 inches long ; tail 3 
inches. 
Mus aquaticus, Merr. Pin. p. 107. — Sibb. Scot. p. 12 — Mus amphibius, 
Linn. Syst. i. p. 82. — Water Hat, Penn. Brit. Zool. i. p. 1 18 — Mus am- 
phibius, Walker's Essays, p. 496. W, Llygoden y dwfr ; G, Hadan 
uisque Frequent in the banks of rivers. Not in the Northern Isles. 
The males are greyish-black on the back, the females yellowish-brown, with 
scattered black hairs, both light coloured beneath. Tail covered with short 
hair, and ending in a small pencil. This species swims and dives well. It 
seems to feed exclusively on the roots of aquatic plants, no remains of the 
bones of little fishes having been detected by us in its excrement, though 
said to prey on such. During the winter months, it retires to a cavity formed 
under ground in a dry bank, in which it has previously deposited a stock of 
provisions. This consists in some cases of potatoes, as v^as observed by Mr 
White, (Hist. Selb. i. p. 129.) ; and we have twice witnessed the same thing. 
In the end of July we have found the stomach of a young one filled with 
clover. It is probable that this species becomes torpid in the cold months. 
35. A. agrestis. Field Vole. — Body 3 inches and a half 
long, tail inch. 
Mus agrestis, Pay., Quad. p. 218 — Short-tailed mouse, Penn. Brit. Zool. 
i. p. 123. B, Llygoden gwlia’r maes. Vole-mouse in Orkney In 
gardens and meadows, common. 
This species never exceeds half the size of the former. The fur is browner 
above and paler beneath, the ears are longer in proportion ; and the tusks, 
which in the former are yellow, are in this nearly white. Doubts were en- 
tertained by Linn^us whether this and the former were distinct species. 
But in his description of his Mus terrestris (our No. 35.), he introduces several of 
the characters of the A. aquatica; and Pennant seems to have described a young 
one of that species for the agrestis. The field vole is most destructive in gar- 
dens to seeds, especially to early peas, which, after germination has com- 
menced, it scents out and digs up. The trap called by gardeners the Fourth 
Figure catches them readily. It is equally destructive to young plantations, 
and to coarse pastures. It multiplies prodigiously in certain seasons, and 
commits extensive ravages. , 
In consequence of the progress of Society, one species has been extirpated 
from the British Glires — the Beaveh ( Castor Fiber). This animal appears, 
from the testimony of Giraldus de Barri, to have existed only in one river 
in Wales and another in Scotland in the 12th century, (Hist. Camb* lib. ii. 
