NORTHUMBERLAND AND DURHAM. 173 
ences were lightly regarded and little noted, and the brown rat 
may possibly, if not probably, have made much progress, and 
obtained a firm settlement before its presence was noticed. The 
remains of neither of the species of house rat have been detected, 
either in the “ Kjdkkenméddings” of Denmark, or the “ Pfahl- 
bauten” of Switzerland, and the habitations of the ancient races 
of men, appear, therefore, to have been free from the troublesome 
invasion of these mischievous and destructive animals; nor, as 
we might expect, have any traces of the domestic cat been found 
among these early dwellings, for the mouse was also then absent 
from the habitations of men. 
“ This species used to inhabit my father’s house in Darlington, 
living in the garrets, either from preference, or driven there by 
the brown rat.” — W. Backhouse. 
5. M. pecumanus, Pall. Brown Rat. Norweecran Rar. 
This species is said to have been introduced into England in 
1730. Though it is often called the Norwegian rat, it is 
_ probably of Eastern origin, and came to Europe by two lines of 
migration—one, proceeding north-west, towards the Baltic, the 
other, west, towards the Mediterranean; following in this respect 
precisely the same lines of march as those barbarian tribes who 
precipitated themselves upon the rich provinces of the Eastern 
Empire, and like the brown rats drove out the old possessors of 
the soil. In one hundred and thirty years, then, if the date be 
correct, has this wonderful animal, by fraud and force, combined 
with prolific multiplication, subjugated these islands, and indeed 
all Western Europe, and reduced to a few miserable fastnesses 
the ancient rat population of the country. 
Famity III. CASTORID A. 
1, ARVICOLA, Lacep. 
1. A. ampuisius, Linn. Water Rat. Water Vote. 
This species is abundant everywhere, about the banks of 
ditches, streams, ponds, and rivers. A piebald variety is noticed 
in the Berwickshire Proceedings, Vol. I. p. 104. 
