154 THE GEOGRAPHY OF MAMMALS 



the tableland of Mexico, the Neotropical Region extends as 

 a narrow strip along the Gulf of Mexico and the Pacific, 

 as far north as the Rio Grande on the former coast, and 

 to about Guaynias on the latter. 



There are no islands of any importance belonging to 

 this Region that need be mentioned here. The Pacific 

 islands on the west coast of Mexico have few, if any, 

 mammals. The large islands of Newfoundland and Van- 

 couver are of the true continental type, being separated 

 from the mainland only by quite shallow water. The 

 Antilles, or West India islands, belong entirely to the 

 Neotropical Region, and have been already considered in 

 a previous chapter. 



Section II. — General View of the Mammal-fauna 



OF THE NEARCTIC REGION 



On referring to the table given at the end of the first 

 chapter, it will be seen that the total number of genera, 

 and also of species contained in the Nearctic Region, is 

 considerably less than in any of the other Regions hitherto 

 treated of. This may be explained partly by the fact that 

 the whole of this Region is practically outside the tropics, 

 whereas the other Regions previously described lie to a 

 great extent within the tropical zone, which is very favour- 

 able to the development of a rich and varied fauna. 



Out of the nine Orders into which the terrestrial 

 Mammals have been divided, two only are not represented 

 in this Region. These are the Primates, at the head of the 

 list, and the Monotremes, at the extreme end, the latter 

 being confined to the Australian Region. The Marsupials 



