272 THE GEOGRAPHY OF MAMMALS 



Region. These two species are closely allied and perhaps 

 scarcely distinguishable. 



The Haplodontiidsz, or Sewellels, allied to the Squirrels, 

 contain only the single genus Haplodontia, the species 

 of which are confined to the Nearctic Region. 



In the fourth family of the Rodents we meet with more 

 familiar objects. The Gliridie, or Dormice, with six genera 

 and about nineteen or twenty species, have a curious 

 distribution, being found only in the Ethiopian, Oriental, 

 and Palsearctic Regions. Each of these Regions, however, 

 has its peculiar genera, true Glis and its allies belonging 

 to the Palsearctic Region, whilst Oraphiurus is strictly 

 Ethiopian, and the two remaining genera are restricted to 

 the Oriental Region. 



We now come to the Mice, or Muridze, which, as already 

 indicated, are exceedingly numerous and all-pervading 

 creatures. Mr. Thomas places the 730 species of this 

 family in seventy-eight genera. Mice are most numerous, 

 perhaps, in the tropics, but are also well represented in 

 Arctic latitudes, and in the shape of Lemmings (Lemmus), 

 extend far towards the Pole. 



They are not abundant in Australia proper, being repre- 

 sented there chiefly by the peculiar genus Hydromys and 

 a few species of Mus. In Madagascar the seven genera of 

 MurkliB met with are likewise altogether restricted to that 

 anomalous island. 



The Mole-rats {Spalacidte), which follow next in 

 Mr. Thomas's series, are a small and peculiar group, 

 the members of which imitate the subterranean life 

 of the Moles. The typical genus Spalax, with eight 

 species, is confined to the PaLearctic Region, whilst 

 the Bamboo Rats (Rhizomys), represent the group in 



