260 THE GREAT NORTH-WEST 



decumanus, Mus musculus, and Mus rattus, have established 

 themselves in several parts of Canada and the States ; 

 not only in coast towns, but also in the interior. In 

 some places they are more abundant than the native 

 species. Of course they have come to America concealed 

 in the cargoes of ships ; and several interesting problems 

 have now to be solved. Will the new species oust the 

 old ? Will the brown rat drive its black brother out of 

 the land, or prevent its obtaining a permanent footing 

 here ? Or will this vast continent find room for all ? 

 Time only can answer these questions ; meanwhile it is 

 certain that the three species I have mentioned, and 

 some others from both Europe and Asia, are propagating 

 fast, though as yet only locally. I was a little sur- 

 prised to find both black and brown rats here ; because, 

 as far as my experience goes, the brown rat is the only 

 rat found on shipboard. He is master, and seems to 

 have frightened the black species from maritime adven- 

 ture. Certainly the two kinds are never, by any chance, 

 found on the same ship. 



