CHAPTER III 

 THE NEOTROPICAL REGION 



(Plate III., p. 82) 



Section I. — Boundaries of the Neotropical Region 



The Neotropical Region is, no doubt, after the Australian, 

 the most distinct of all the regions. It includes not only 

 the continent of South America, but the West Indies, 

 Central America, and a considerable portion of Southern 

 Mexico. As regards its northern termination, on account 

 of the great admixture of Nearctic and Neotropical forms 

 which takes place where the two Regions join, it is impos- 

 sible to lay down anything but an approximate boundary. 

 Mr. Wallace (11) draws the line from the mouth of the 

 Rio Grande on the Atlantic side to the neighbourhood of 

 Mazatlan, in about the same latitude, on the Pacific side, 

 but bends it down between these two points so as to 

 include in the Nearctic Region the whole of the high 

 tableland down to the city of Mexico. 



Some American naturalists, among others Merriam and 

 Allen (1), include in the Neotropical Region the southern 

 extremities of the peninsulas of Lower California and of 

 Florida. This, however, appears to be unnecessary, at least 

 so far as the mammals are concerned, though there are 

 certainly a considerable number of Neotropical birds and 

 insects found in both these districts. 



Besides the mainland of Central and South America 



