RATS, MICE. 355 



Guinea. Tasmania has several species, and one or more forms (M. 

 NovEB-ZelandisB, M. Maorium) appear also to be indigenous to New 

 Zealand; M. Salamonis inhabits the island of Ugi, in the Solomon 

 group. The better known members of the group, the Norway or 

 brown rat (Mus decumanus), and black rat (Mus rattus), whose ongi- 

 nal home seems to have been Southern or Central Asia, and the com- 

 mon mouse (Mus musculus), probably a native of India, have been 

 spread through man's intervention over the greater portion of the 

 inhabited globe, rapidly displacing in many quarters the indigenous 

 races of similar or allied forms that originally occupied the con- 

 quered territory. The black rat, which appears to have been the 

 earliest intruder, is now largely supplanted by the brown species ; 

 in England there would appear to be but a single colony left.* The 

 wood-mouse (Mus sylvatious) and harvest-mouse (M. minutus), the 

 latter the smallest of the European species of mice, are distributed 

 over the greater portion of Europe and Northern Asia. The largest 

 member of the rat tribe is the great bandicoot or pig-rat of the 

 Indian peninsula (Nesokia bandicota), which frequently exceeds 

 one foot in length. Other distinctive rat-like forms of the Old 

 World are the spiny-mice (Acauthomys), which are confined prin- 

 cipally to Syria (Palestine), and the east coast of Africa ; the jump- 

 ing-mice (Meriones or Gerbillus) of the continent of Africa, the 

 warmer tracts of Southern and Southwestern Asia, and the steppe 

 region about the Caspian Sea ; and the jumping -rats of Australia 

 (Hapalotis), which recall in general appearance the jerboas. 



The Old "World forms of the genus Mus are represented in the 

 New World by the vesper-mice (Hesperomys), which very closely 

 resemble them in general character, but differ in certain peculiari- 

 ties of dental structure, which likewise serve to distinguish most 

 of the American rats; some seventy or more species and varieties 

 have been described, ranging collectively from the Arctic regions 

 to the Strait of Magellan. Hesperomys leucopus, the white-footed 

 or deer mouse, inhabits the greater portion of the North American 



* While in most regions where the black and the "brown rat have been in- 

 troduced the latter has been rapidly driving out or exterminating the for- 

 mer, it would appear that in some parts of Central Geimany the reverse phe- 

 nomenon is presented — that is to say, the black rat ie regaining its ascendancy 

 over the brown species (Magnus, " Sitzungsber. d. Gesell. naturf. freunde," 

 1883, p. 47). 



