VI. 



The Nearctic Region and its Mammals/ 



IT would appear that the Munroe doctrine of " America for the 

 Americans," is httle heeded by the biologists of that Continent. 

 Although the best European authorities on the geographical distribu- 

 tion of animals have long ago conceded to the northern half of the 

 New World the rank of one of the six primary divisions of the earth's 

 surface, under the name of the " Nearctic Region," our American 

 friends will have none of it. Two recent writers of deservedly great 

 authority on the Mammal-life of North America, though, as we shall 

 show presently, they differ much in minor details, agree in repudia- 

 ting the Nearctic Region altogether. They refer the northern parts of 

 North America to the " Arctic Realm " or " Boreal Region," of the 

 Old World, and the southern portion to the " American Tropical 

 Realm " or " Tropical Region," leaving only the intermediate area 

 separate and apart. This intermediate area is included by Mr. 

 Allen in his " North Temperate Realm," which embraces the whole 

 of the northern hemisphere on both sides of the Atlantic, between 

 the annual isotherms of 32° and 70°, but is allowed to rank inde- 

 pendently as the " North American Region," while Dr. Merriam, 

 following Cope, calls it the " Sonoran Region." Thus both these 

 authorities agree in splitting up the Nearctic Region into three con- 

 stituent parts, and in repudiating the views of Sclater and Wallace 

 that it should form one of the main zoo-geographical divisions of the 

 earth's surface. While, however, it must be allowed that both Mr. 

 Allen and Dr. Merriam have studied the distribution of Mammal-life 

 in North America to some effect, and are well acquainted with its 

 details, it will be easy to show that their general views on geographi- 

 cal distribution are not entitled to acceptance. At the same time, we 

 admit that there is something to be said on their side of the question. 

 Taking a general view of the distribution of Mammal-life over 

 the terrestrial portion of the earth's surface, we see at once that 

 Australia and the adjacent islands stand strongly apart from the rest 



1 i. " The Geographic Distribution of Life in North America, with Special 

 Reference to the MammaHa." By C. Hart Merriam, M.D. Pivc. Biol. Soc. 

 Washington, vol. vii., p. i (April, 1892). 



ii. " The Geographical Distribution of North American Mammals." By Joel 

 Asaph Allen. Bull. Anicr. Mus. Nat Hist., vol. iv., no. i (Dec, 1892). 



