Sonic of Wallace s Fallacies. 



411 



7ah/r S/i')iriii{) Xitinher of Distiiictivi' Families and Genera of Maniuiala and 

 Birds of flu' Arid Sonoraii Conipnred icifh Ihe Humid Sonorari, and of Ihr 

 tSontn-ait as a Whah' Compared irith tJtr Boreal as a Wliolr. 



Descending to species, the contrast is even more marked. 



The above table shows, so far as the genera of mammals and 

 l)irds are concerned, that the difference between the humid 

 ' Atlantic ' or ' Eastern Province * on the one liand and the 

 arid Great Plains and Great Basin on the other is less than one- 

 fourth as great as the difference betAveen tlie Sonoi-an and Boreal 

 Regions. 



These facts, it seems to me. sliouhl suffice to establish beyond 

 dispute the subordinate ])art jilayed 1>y humidity in compari- 

 sion to temperature, and should dispel any lingering doubts 

 tliat may still liaunt the minds of conservative naturalists re- 

 sjiecting the necessity of aliandoning the long accei)ted division 

 of the United States into Atlantic, Central, and Pacific provinces. 



Remarks respecting some of Wallace's Fallacies. 



Wallace, in his great work on Geographic Distribution, and in 

 subsequent writings on the same subject, greatly underrates the 

 importance of temperature as a factor in determining the distri- 



'■''Sifomys and Lijn.r are omitted because they range ovtr most of the 

 forested part of the Boreal Region. 



t J'li/nriiis isomitted berauseit ranges over mucii of theSonoran Uegoiu. 



7— liidi,. Soc, Wvsrr.. Voi. VH. ISiiJ. 



