THE COMMON MOUSE. 51 



other. All are nocturnal, and most, if not all, subter- 

 ranean in their habits, and also gregarious. Some 

 frequent the fields and woods, some the gardens, 

 and some the abodes of man, undermining floors and 

 walls, and breeding within the precincts of his habitation. 

 They are spread through every quarter of the globe; 

 and the common mouse and the brown rat have been in- 

 troduced by the indirect agency of man, even into the 

 remotest and most desolate islands. (See ' Zoology of 

 the Voyage of H.M.S. Beagle — Mammalia,' No. ii. 

 of pt. ii., p. 31, et seq.) With respect to the brown 

 rat (Mus decwnanus), sometimes erroneously called the 

 Norway rat, it appears to have been originally transported 

 from Persia or India into Europe ; its place was previ- 

 ously occupied by the black rat (Mus rattus), a smaller 

 and more timid animal, and in some districts now quite 

 extirpated by its more powerful rival. The brown rat 

 was not known in England before 1730, nor in France 

 before 1750. According to Pallas, it did not appear in 

 Russia and Siberia till 1766 ; and Dr. Harlan states that 

 it did not make its appearance in North America till 

 1775. When Dr. Richardson wrote his ' Fauna Boreali- 

 Americana,' it was common in Lower Canada, but 

 had not advanced much beyond Kingston in Upper 

 Canada. He did not observe it in the fur countries, and 

 believes, if it exists there, that it is only at the mouth 

 of the Columbia river or at the factories on the shores 

 of Hudson's Bay. Mr. Darwin found it at Buenos 

 Ay res, Valparaiso, East Falkland Island, and Keeling 

 Island. With respect to the black rat, even that is in 

 all probability of foreign origin. It was not known in 

 Western Europe before the middle of the sixteenth 

 century, and Gesner was the first who described and 

 figured it. 



In the Island of Ascension, in the Atlantic Ocean, 

 Mr. Darwin found two varieties, as he and Mr. Water- 

 house consider, of the black rat {Musrattus). These 

 two animals ditier in the colour of the fur, one being of 

 a grizzled brownish colour, the other black, with more 

 soft or glossy I'ur. " The specimen which has a black 

 and glossy fur frequents the short coarse grass near the 



