MICE AND RATS. I9I 



seven at a birth, and thus in favourable localities soon increases 

 to a great extent. Its nest is composed of straw, hay, woollen 

 cloth, linen, and other substances, generally gnawed into small 

 fragments ; and the young are at first blind and naked, but 

 grow so rapidly that in a fortnight they are able to shift for them- 

 selves." 



To this it may be added that subsequent observations have 

 shown that the number of young in a litter may vary from four 

 to seven, and that the female commences to breed consider- 

 ably before a year old. 



When poisoned in houses, both Rats and Mice have an un- 

 pleasant habit of retiring behind skirting-boards, canvased 

 walls, and similar situations, to die. To detect their exact 

 position when this happens, the best plan is to close the door 

 and windows, and to introduce into the room two or three blue- 

 bottle flies, which will soon settle on the spot behind which 

 lies the defunct Rodent. 



v. THE BLACK RAT. MUS RATTUS. 



Mus rat/us, Linn., Syst. Nat. ed. 12, vol. i. p. 83 (1766); 



Bell, British Quadrupeds, 2nd ed. p. 302 (1874); Blan- 



ford, Mamm. Brit. India, p. 406 (i8gi). 

 Mus alexandrinus, Geoffroy, Descr. de I'Egypte, vol. ii. p. 



753 (1812). 

 Mus rufescens, Gray, Mag. Nat. Hist. vol. i. p. 585 (1837). 

 Mus nitidiis, Gray, Ann. Mag. Nat. Hist. vol. xv. p. 267 



(1845); &c., &c., &c. 



{Plate XX in.) 



Characters. — Size large ; build relatively light ; head slender 

 ears large ; tail thin and exceeding the head and body in 

 length. In the typical English variety the fur of the upper- 

 parts is greyish-black, and below ash-colour. Size very variable ; 



