2 42 BRITISH MAMMALS 



It was carried in ships to America in the middle of the sixteenth 

 century, and is now found throughout the New World and the 

 West Indies concurrently with the brown rat. In the British 

 Islands it lingers in small numbers in parts of Ireland, Scotland, 

 and Northern England, but has been nearly destroyed by the 

 brown rat, which has also exterminated it in many parts of 

 Europe. 



Mu5 musculus. The Common Mouse 



' A pretty, but annoying little pest," is the very apt definition 

 of this commonest of Rodents given by several writers on British 

 Zoology. The Common Mouse has nothing of the repulsiveness, 

 or even horror, that attaches to the brown rat. It may be very 

 annoying through the mess and litter which it makes and the 

 damage it may do to food, but it is of engaging appearance and 

 ways which can even be winsome. Its length from the tip' of the 

 nose to the root of the tail is about 3^ in., and the tail is nearly 

 as much again. It differs from the wood mouse, which is about 

 to be described, by its smaller ears and eyes, the limbs and tail 

 being also somewhat shorter. Its coloration is less bright, being 

 an almost uniform grayish-brown, somewhat lighter on the belly. 

 The singular glossiness of the fur, however, gives it the appearance 

 of being " well groomed." It is, in fact, a very elegant little 

 creature. There is a great tendency to variation in the common 

 mouse, both in colour and size. Some varieties of it inhabiting 

 islands or mountain districts are smaller than the house mouse or 

 than those which frequent stacks and granaries. Amongst other 

 variations of colour than albinism — and white mice seldom 

 maintain this for long amongst their coloured brethren — there 

 are pale gray or pale buif varieties and others in which the back 

 is dark brown flecked with white, or dark sepia. There are long 

 whiskers, or vibrissse, but these are not developed quite so 

 extravagantly as in the wood mouse. 



The common mouse has large naked ears, though this feature 

 is not so marked as in the wood mouse. The ears are rounded, 



