THE BROWN RAT. 



451 



published in Hay den's Geological Keports, 1877, furnishes a vast anrount of valuable matter 

 on the subject. 



Members of this order belong to all portions of the globe, and are particularly abundant 

 in America, where there are said to be as many as are known to all parts of the world. The 

 order contains more species than any other class of mammals, between eight and nine hundred 

 being known, and they are very evenly distributed. In South America there are more than in 

 the northern half of the New World ; but the great number of species included in the one 

 genus, Hesperomys, cause this preponderance. 



There are no indigenous Rodents common to both Europe and America, excepting the 

 beaver, which is regarded by some as the same in both countries. The Musk Rat and a species 

 of Spermophilus are said to occur in Kamtschatka ; in this event these would hold as excep- 

 tions. There are no South American species in North America, but a close relationship exists 

 between the genera. Wallace gives the following, as regard the family of Rodents, and number 

 of genera and species. Muridie, the Mouse family, has thirty -seven genera, and three hundred 



" 



BLACK RAT.-J/ws rattus. 



BROWN HAT. Jftw decumunim. 



and thirty species. The true Mouse (the species common to our houses), he records as not 

 found indigenous in North nor South America, nor the three insular groups belonging to the 

 Australian region, but it is indigenous in the remaining portions of the globe very widely. 

 Hesperomys represents it in the New World eighty or more species are enumerated. The 

 Pocket Mouse family, (SaccomyidcB) has six genera and thirty-three species, all in North 

 America. The Beaver family (Castoridat) has one gemis and two species, in America and 

 Europe. The Squirrels (SduridcK) have eight genera and nearly two hundred species. 

 These are largely from North America, and Europe and Asia. They are not found in the 

 West Indies, in Australia, and in South America as far north as Paraguay. 



FEW animals are so well known or so thoroughly detested as the common BROWN RAT, or 

 NORWAY RAT, as it is sometimes erroneously called. 



It has spread itself over almost every portion of the globe, taking passages in almost every 

 ship that traverses the ocean, and landing on almost every shore which the vessel may touch. 

 Wherever they set their feet, the Brown Rats take up their abode ; and, being singularly pro- 

 lific animals, soon establish themselves in perpetuity. They are marvellous exterminators of 



