RATS 137 



little longer than the body and head. It is 

 smaller and more elegantly built than the 

 brown rat ; its snout is longer and more slender, 

 and the long, thin, scaly tail is about eight or 

 nine inches in length. The British forms 

 average in length seven inches from the tip of 

 the nose to the origin of the tail. Although 

 known as the black rat, its bluish, or greyish- 

 black colour is, both in the East and in Northern 

 America, frequently replaced by brown on the 

 upper surface, and by white fur on the lower, 

 or by a yellowish-brown rufous colour. The 

 ears, feet, and tail are black. When kept as 

 pets — and they frequently are — white and 

 piebald varieties are often bred. The ears are 

 larger in proportion than in M, decumanus, 

 the rings of scales on the tail better marked, 

 and spines in the fur are not uncommon. 



The black rat, or Old-English rat, begins 

 to breed under the age of one year, and goes 

 with young six weeks ; it breeds frequently 

 during the year, but does not commence in 

 Bombay, according to the Plague Commission, 

 until it has attained the weight of at least 

 70 grammes. In India they breed all the year 

 round. In Britain they produce six to eleven 

 young at a time ; in India the average is 5*2 ; 

 the largest number found by the Plague Com- 

 mission having been nine. In Bombay it is 

 noteworthy that in both species the percentage 



