SQUIRRELS, BEAVERS, DORMICE, AND RATS 239 



Mus decumanus. The Brown Rat 



This creature is almost an unmitigated pest, and is one of the 

 few mammals that it would be virtuous to completely extinguish. It 

 is almost the largest form amongst the True Mice, measuring 

 when fully grown about 9 in. from the tip of the nose to the 

 root of the tail, and over 7 in. in addition along the tail to its 

 extremity. Its head is very long, as compared with other mice, 

 and is furnished with a powerful lower jaw. The snout is ugly, 

 and nearly naked. The black eyes are very prominent, seeming 

 almost to bulge from the head, and not being sheltered within 

 any marked cavity in the brows. The ears are round, large, 

 and set well back. The mouth opens far behind the snout, and 

 the cleft upper lip is consequently long. The general colour 

 is grayish or umber-brown, darkened here and there by the 

 presence of long hairs that are blackish in colour. On the under 

 surface it is gray. The tail is flesh-colour, with the small scales 

 set in overlapping rings. On the coasts of Ireland this rat 

 sometimes develops a black variety with a whitish patch on the 

 chest. The prominent eyes, the long, blunt snout, the scaly tail, 

 the dingy brown colour, and the savage disposition of this rat, 

 combine to make it a repulsive creature. It is said to be cleanly 

 in its habits, though it frequents the filthiest adjuncts of 

 humanity. 



The Brown Rat, like some other members of the genus Mus, 

 has six pairs of mammae,^ and is exceedingly prolific. It breeds 

 as often as four times a year, and the litter may contain from 

 eight to fourteen young ones. The female rat can breed before 

 she is fully grown, at six months old. As regards food, they are 

 omnivorous, and will eat flesh as greedily as parchment, leather, 

 grass, seaweed, shell-fish, corn, roots, bones, ivory, fruit, sewage, 

 and fish. The rat's carnivorous propensities leads it to attack, 

 kiU, and devour birds and all the smaller mammalia with which 

 it may come into contact, and even man himself. Snakes and 



^ According to Owen. Some zoologists reduce the number to five pairs. 

 There is quite possibly local variation. 



