306 ORDER X. 



ing 107 species ; we think, by no means the 

 whole. 



In the next \ve have the 



2d, MuRiDjE or Rats, with the molars varying in 

 the different genera from f-f to f-f, the first of which 

 is Myoxm or the Dormouse, and Graphwrus, not 

 generically different. They are still destitute of an- 

 terior thumhs, and have a well furnished brush to 

 the tail. 



M. glis, or the Fat Dormouse, described in Vo- 

 lume VII., is one of the best known of the eight or 

 ten species enumerated. The genus DIPUS, twelve 

 species, and MERTONIS, two species, include the 

 graceful Jerboas, or Jumping Mice of Africa, Cen- 

 tral Asia, and North America. Here we think may 

 bo placed Helamys or Pedetes, the Spfinghaas of the 

 Cape; and next Mus, the Rats and Mice Proper, 

 sub-divided into Mus hisperomys, Dendromys, Ger- 

 billus, ReithromyS) Psammomys, Phlceomys^ Sig- 

 modon, Euryotis and Rhizomys, form at least njnety 

 species of every quarter of the world, and in great- 

 est number in South America and the West India 

 Islands ; and Cricetus, or the Hamsters, reckon eight 

 more. 



3d, The ARVICOLIDJE, Voles or Campagnols, with 

 molars f-f, enumerate first, the 



Genus CASTOR, or Beaver, the most important 

 animal to the fur traders ; and remarkable for its 

 bulk, trowel-shaped scaly tail, and instinctive habits 

 of building in society, making dams to keep the 

 water up a^d for the superstitions to which these 



