32 MAMMALIA GLIRES. [Mirs. 



below. Obs. The colours vary a little in different specimens, and some- 

 times individuals occur wholly white ; or white with dark spots. 



Found in houses and stacks. Those which occur in the latter situation 

 are remarkable for the brightness of their colour, which has a more 

 decided yellow tinge than in house specimens. They also sometimes 

 attain a larger size, measuring nearly four inches in length. Feeds 

 on various animal and vegetable substances. Breeds several times in 

 the year, and is extremely prolific. 



44. M. Rattus, Linn. (Black Rat.) Fur grayish- 

 black above ; ash-colour beneath : tail a little longer than 

 the body. 



M. Rattus, Desm. Mammal, p. 300. Flem. Brit. An. p. 20. Black 

 Rat, Penn. Brit. Zool. vol. i. p. 113. Shaw, Gen. Zool. vol. n. 

 p. 52. pi. 130. 



DIMENS. Length of the head and body seven inches four lines ; of 

 the head one inch ten lines ; of the ears eleven lines and a half; of the 

 tail seven inches eleven lines. 



DESCRIPT. Head long ; muzzle sharp-pointed ; lower jaw very short ; 

 eyes large and prominent ; ears oval, broad, and naked : whiskers long : 

 fore feet with four toes, and a claw in the place of a thumb ; hind feet 

 with five : tail longer than the body, almost entirely naked, and covered 

 with small scales disposed in rings. Colour of the upper parts deep iron- 

 gray, or grayish black ; those beneath dull ash-colour : feet and tail 

 dusky. 



Frequents houses, and is truly indigenous ; but is now much less 

 general than the next species. Food various. Breeds frequently in 

 the year, producing from six to eleven at a time. 



* 45. M. decumanus, Pall. (Brown Rat.) Fur above grayish brown, 

 tinged with yellow ; beneath whitish : tail scarcely so long as the body. 



M. decumanus, Desm. Mammal, p. 299. Flem. Brit. An. p. 20. Norway 

 Rat, Penn. Brit. Zool. vol. i. p. 115. Shaw, Gen. Zool. vol. n. p. 51. 

 pi. 130. 



DIMENS. Length of the head and body eleven inches ; of the head two inches 

 four lines and a half ; of the ears eight lines and a half ; of the tail eight inches 

 four lines. 



DESCRIPT. Larger than the last species ; thicker and of a stronger make : muzzle 

 not quite so sharp at the extremity : eyes large and prominent : ears as broad as 

 long, rounded at the extremity, and almost naked : tail naked and scaly, with about 

 one hundred and eighty rings, generally not quite so long as the body, sometimes 

 equalling it in length. Hair on the upper parts dusky ash at the roots, and reddish 

 yellow at the extremity, with longer hairs intermixed of a deep brown colour 

 throughout their whole length ; general resulting tint grayish brown with a cast 

 of tawny yellow ; under parts dirty white, inclining here and there to ash- 

 colour. 



Introduced originally by shipping from Asia : unknown in England before the 

 year 1730. Abundant now throughout the country, inhabiting houses, barns, 

 granaries, drains, and other situations. Habits similar to those of the last species 

 Takes occasionally to the water, and swims readily . 



