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. II. p. 51. pi. 130.
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.
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.