100 RODENTIA. 



it was no doubt introduced into Italy with merchandise, 

 and has di-iven away the M. Rattus from the south of that 

 country ; it occurs, however, along mth the Brown Rat. 

 Is often found in numbers in vessels from Egypt when 

 discharging their cargoes of corn in British ports, but does 

 not appear to spread in those towns, being probably kept 

 down by the common species. 



Mus musculus. 



Mus musculus, Desm. Mamm. Sp. 478 ; Bell, Brit. Quad. 

 Common Mouse. 



Description. — Tail almost as long as the body, dark grey, 

 with scaly rings, and slightly furnished with short hairs ; 

 ears about half as long as the head, shaped like those of 

 M. Rattus, which in its proportions it much resembles, 

 though in miniature ; head taper ; muzzle rather acute ; 

 the ears and eyes are smaller than in M. sylvaticus, the 

 former rounded, but shorter and narrower than in that 

 species, clothed with fine, soft, short hair. Fur grejish 

 brown above, grey beneath. White, buff, and spotted 

 varieties occur. 



Length of head and body, 3 inches 2 lines ; head, 11 

 lines ; ears, 5 lines ; tail, 2 inches 11 lines. 



The Mouse seems to have followed man wherever he 

 has penetrated, and is to be found aU over the world in 

 every climate. It is very prolific, breeding several times 

 in the year, and producing five or six young at a birth. 

 The Prince of Musignano mentions a variety with the 

 belly red-brown, as very common in Italy, and in par- 

 ticular at Florence. 



Mus Islandicus. 



Mus Islandicus, Thienemann ; De Selys, Micromm. 

 Desceiption. — Size of M. musculus. Tail as long as the 

 body, nearly naked, scales ash-brown above, white be- 



