CHAPTER VI 



THE NEARCTIC REGION 



(Plate VI, p. 176) 



Section I. — Boundaries of the Nearctic Region 



With the Nearctic Region we enter upon a subject on 

 which there has been a great deal of controversy among the 

 students of geographical distribution. As was pointed out 

 in the introductory article of this volume, a certain number 

 of writers maintain that this Region does not contain a 

 sufficient quantity of distinctive and indigenous forms to 

 entitle it to separation from the Palsearctic Region. What 

 should constitute a sufficient number of distinctive forms 

 depends, of course, largely on the individual opinions of 

 the writers, but if allowance be made for the undoubted 

 similarities of the extreme northern parts of the Old and 

 New Worlds, which together may be considered as form- 

 ing a kind of intermediate district, the facts and figures 

 given below will, we think, convince every one that the 

 land-surfaces of the Palrearctic and Nearctic Regions have 

 now, and have had in the past, quite sufficiently dis- 

 tinct faunas to warrant their division into two primary 

 Regions. 



The boundaries of the Nearctic Region are compara- 

 tively simple. They embrace the whole of North America 

 as far as the southern limit of the tableland of Mexico, 

 with which Greenland may be included. On either side of 



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