488 MURIDA®—ARVICOLA 
of similar size, and, not being by any means lacking in climbing 
powers, it regularly takes refuge in the stumps of old willow 
trees.’ During protracted floods large numbers are sometimes 
destroyed, but the altered conditions seem never to last long 
enough to effect the animal’s extinction, and its numbers recover 
in the security of the ponds and ditches and sluggish rivers, 
which, rather than swift, gravelly streams, are its favourite 
summer haunts. But it is not tied to these, and when abundant 
may be found almost anywhere within a reasonable distance of 
water—in gardens, corn-fields, coastal marshes, hill-streams, 
or even sand-hills by the sea-shore.* In the north-western 
Highlands it frequents the limestone burns, where it takes 
shelter in holes in the limestone.® 
It is at all times an expert swimmer and diver, vastly more 
so, as Mr A. H. Cocks has observed, than the scarcely less 
aquatic Brown Rat,* but, although it progresses rapidly under 
the surface, its methods are those of ordinary terrestrial 
mammals, since it uses all four limbs for purposes of propulsion, 
and on the surface swims with its head and upper part of its back 
above the surface. Mr Aubyn Trevor-Battye° has, however, 
observed that, when it is not in a hurry, its fore legs may rest 
at its sides, the hind legs doing all the work.® There is no 
evidence to show how long it is capable of remaining below the 
surface. If frightened, it usually contrives to emerge under 
some cover." 
Although the young are for some time comparatively help- 
less, they can swim at an early date, even before their eyes 
open.’ Monsieur Fernand Lataste has described the first 
attempts in this direction of a young male of the allied con- 
tinental Water Rat.° This was taken from its nest before its 
1 E. Hollis (7S.) took one from a hole in an oak, 12 feet above the ground, 
The tree not being hollow, the rat must have climbed up by the outside. 
2 H. A. Macpherson ; W. Evans. 
3 J. A. Harvie-Brown and Macpherson, Worth-west Highlands, 1904, 42. 
4 Millais (ii., 292) strangely puts the facts in exactly the opposite way. 
5 Pictures in Prose, 1894, 215. 
6 Beavers swim with the fore paws motionless under the chin (L, E. Adams). 
7 According to Mr Douglas English, Some Smaller British Mammals (undated), 
if cover is absent, it will bring up a leaf or other material in its mouth from the 
bottom. 
8H. G. M. Williams, Zoologéts?¢, 1857, 5788. » A. sapidus. 

