Vol. X 

 >S93 



Allen, Origin and Distribution of N. A. Birds. ^45 



names, as 'Hudsonian,' etc., are admirably appropriate when 

 suggestive of some characteristic portion of the region in ques- 

 tion. Terms designating grade should, of course, be used with 

 the same strictness as the corresponding terms, — order, family, 

 genus, etc., expressive of rank, — in biology. 



Realm is employed as a designation for primary regions, taking 

 the world at large, and Fauna for the ultimate subdivisions. 

 Region, the term selected for divisions of the second rank, has 

 been used by different writers for areas of various grades, but it 

 is proposed to limit its application in a technical sense to the 

 primary divisions of Realms. Below this, in successively 

 descending order, we have Subregions, Provinces, Subprovinces, 

 Districts and Faunae; faunas being subdivisions of districts (in 

 cases when it seems desirable to recognize districts), while dis- 

 tricts are the primary subdivisions of the subprovinces. In the 

 Arctic Realm the only subdivisions it seems necessary to recog- 

 nize are faunae ; in the Cold Temperate, possibly both districts 

 and faunae ; in the Warm Temperate, at least so far as North 

 America is concerned, it seems desirable to recognize (i) 

 provinces, (2) subprovinces, (3) districts, and (4) faunae. 



As early as 1S7S 1 I separated the 'North American Region' 

 into two Subregions, namely, a Cold Temperate S?ibregio?i 

 and a Warm Temperate Subregion, as is done in the present 

 paper, using these terms as headings in tables giving the distri- 

 bution of the genera of North American mammals. Baird's 'East- 

 ern,' 'Middle,' and 'Western' Provinces were recognized as 

 "natural regions," with the designation of 'Provinces,' but with 

 the Eastern Province modified so as to restrict it to the Warm 

 Temperate Subregion, and all three reduced in grade to regions 

 of the third rank 2 instead of the second rank as regarded by 

 Professor Baird. 



In 1883 Dr. Packard 3 substantially adopted this classification 

 in treating of the faunal regions of North America, with, how- 

 ever, a change of name for the 'Cold Temperate Subregion,' he 



1 Bull. U. S. Geol. and Geogr. Survey (Hayden), IV, 1878, pp. 338-344. 



2 That is, of the North American Region; really of fourth rank, considered from the 

 basis of the world as a whole. 



3 Twelth Ann. Rep. U. S. Geol. and Geogr. Survey (Hayden), pt. I, 1883, pp. 362- 

 370, and map; the latter republished in the Third Rep. U. S. Entomol. Coram., 1883, 

 map iv. 



*9 



