186 MR. R. SWINHOE ON A NEW RAT FROM FORMOSA. [May 10, 
fore paws, belly, and under thighs pure white; paws white, the 
hinder ones large. 
In a young animal, measuring 6} inches in trunk, the tail mea- 
sured 6 inches; head to fore root of ear 14 inch; between ears 
‘7 inch; length of ear ‘8 inch; greatest breadth of ear 4 inch; 
hind foot, from tibial joint to end of nails, 1-4 inch. As the animal 
attains its full size, the tail exceeds the trunk in length. I have 
examined about thirty-five specimens of different ages; the younger 
the animal, the fewer spinous bristles : of these the males carry most ; 
they are sharp and very stiff. Amongst these specimens there is, 
as usual, an amount of variation; but in proportions it is not very 
appreciable, except in so far as to be accounted for by age. In colour, 
on the contrary, varieties abound: the most strongly marked are the 
following :— 
1. Sides strongly freckled with olive-yellow. 
2. Brown, with more or less reddish ; fur softer, with few bristles. 
3. Similar to 1, but with brown instead of white fur. 
4. Similar to 1, with white and brown feet and white-patched 
tail. 
5. Characters of nos. 2 and 1 united. 
These five varieties are so linked together by intermediate forms 
that there is no drawing a line between them. When I received the 
first soft-furred brown Rat, I thought I had got a distinct creature ; 
but I soon procured others combining the characters of both. The 
colour and softness of its fur led me to conjecture that it might be a 
race of which the ancestors had hybridized with Mus decumanus, be- 
cause I received a specimen of this last animal from the same locality. 
But the acquisition of further specimens showed me that, from the ~ 
unsullied whiteness of its belly and the intermediate tinges of the 
upper parts of many others, the difference only consisted in a slight 
variation in the colour and appearance of the fur, the other charac- 
teristics of the species remaining unaltered. This Rat is not now 
found in the vicinity of towns, whence, like the indigenous Rats of 
most countries, it has fallen back before the usurpation of the stronger 
hordes of the commercial Rat (Mus decumanus) ; and it is now only 
found in the isolated hamlets of the interior, whither its enemy ap- 
pears gradually to be extending its sway. It is difficult to under- 
stand how so large and strong a Rat has been ousted out of its rights 
by a not much stronger usurper. This species must have occurred 
formerly in towns in pretty considerable numbers, as it still does in 
country places. The imported hortles of Mus decumanus could not 
have been in larger numbers, but I should fancy must have employed 
a superior cunning to deprive these of their territory—much the 
same sort of advantage, probably, that civilization gives the China- 
man in this country, and the whites in Australia, which enables them 
to drive into the mountains and bush the rightful but less expert 
possessors of the land of their fathers. This Rat is allied to the 
aboriginal Rat of Southern China (Mus flavescens, Gray), and doubt- 
less of the same stock; but it attains a larger size, is robuster, has 
larger hind feet, larger ears, and is otherwise distinguished by its 
