DESCRIPTION. 13 



W. T. Blanford states that the species is at present unknown in 

 Persia, and that, as concerns India, the black rat is the generally 

 distributed species, while the brown rat is found only along the coast 

 and the navigable rivers. This statement seems to imply that the 

 latter is a comparatively recent immigrant into India. Early Greek 

 and Roman writers make no mention of the rat, but it is possible that 

 they knew the animal and included it in their references to mice. 



As regards the time of the brown rat's introduction into Europe, 

 we have two known facts. The species reached England from some 

 eastern port about 1728 or 1729, and a little earlier it crossed the 

 Russian frontier from Asia. Pallas, the naturalist and traveler, 

 states that it first reached Europe from the east by way of the Volga, 

 which river it crossed in 1727, and soon afterwards spread over the 

 greater part of Russia. 6 In view of the statement of Blanford, 

 already referred to, it is highly probable* that previous to this migra- 

 tion the Asiatic home of the species was northward rather than 

 southward of the mountain barriers of northern India. This view 

 has been advanced by several naturalists and is further strengthened 

 by the fact that the animal appears to nourish better in a temperate 

 than in a tropical climate. 



The brown rat is said to have first appeared in Paris in 1750. It 

 was brought to the United States, probably from England, about 

 the beginning of the Revolution, 1775. According to Audubon, it 

 was unknown on the Pacific coast of the United States in 1851, 

 although its introduction there must have occurred soon afterwards. 



GENERAL DESCRIPTION. 



The brown rat differs from the other two species in America in 

 larger size, shorter head, more obtuse muzzle, smaller ears, and rela- 

 tively shorter tail. The general color is grayish brown above and 

 whitish below. The overhairs of the upper parts have black tips. 

 The tail is usually shorter than the head and body combined, while 

 in the other two species it is generally longer. 



The black rat is usually of a sooty or plumbeous black color, paler 

 on the underparts; while the roof rat is slightly grayer than the 

 brown rat above and yellowish white on the feet and belly. 



The skull of the brown rat shows well-marked differences from 

 those of the other two species, but the skulls of the roof rat and the 

 black rat are not readily distinguished from each other. Many 

 zoologists regard the black rat as only a geographic race of the roof 

 rat. The two forms interbreed freely. 



The tame white rats of the bird stores are said to be mostly of the 

 Mus rattus type; but albino and spotted specimens of the brown 



« Fauna of British India, Mammals, p. 409, 1891. 

 o Zoographica Rosso- Asiatica, Vol. I, p. 165, 1831. 



