V fg" X 1 Allen, Origin and Distribution of 'N. A. Birds. 1 43 



Zone' for the Hudsonian, 'Arctic-alpine' for treeless mountain 

 summits equivalent in character to the Arctic, etc., or from those 

 of the Atlantic coast faunae. This latter method has the merit 

 of at once suggesting a well-known standard of comparison when 

 applied to belts in the interior or on the Pacific coast, representa- 

 tive of the commonly recognized fauna? of the Atlantic coast. 

 Dr. Merriam has already recognized the equivalents of the 

 Arctic, Hudsonian, Canadian, Alleghanian, etc., in portions of 

 the mountainous districts of the West, and has presented in sub- 

 stance the following correlations. 1 



Zone. Fauna. 



A1 P ine } Arctic. 



Subalpine or Timber-line > 



Hudsonian or Spruce Hudsonian. 



Canadian or Fir Canadian. 



Neutral or Pine Alleghanian. 



Pinon or Cedar [Carolinian]. 



Desert [Louisianian]. 



2. Classification and Nomenclature. 



A few words in regard to the names chosen for the several 

 major divisions of the North American Region, and the choice of 

 names in general in bio-geography. It is natural that the influ- 

 ences controlling the geographical distribution of life, namely, 

 climate, and hence the principal climatic zones, should suggest 

 the names of many of the larger ontological regions ; and we find 

 that to a large extent such names have been chosen, as by Dana, 

 in 1852, in discussing the distribution of marine life, and by bot- 

 anists generally, and notably by German writers. For the lesser 

 regions geographical names, as Hudsonian, etc., are admirably 

 appropriate when suggestive of some characteristic portion of 

 the region in question. Whenever feasible, names first given 

 should be retained in preference to later names. 



In concluding this paper a few words of explanation are neces- 

 sary in relation to various points of nomenclature and classifica- 

 tion. In comparing the present scheme of fauna 1 areas of North 



1 N. Am. Fauna, No. 3, 1890, pp. 7-34, and maps 1-4; ibid, No. 5, 1891, pp. 9-12, 

 21-25. 



