14.6 Allen, Origin and Distribution of N. A. Birds. [April 



adopting for it that of 'Boreal Province' — an unfortunate sug- 

 gestion of my own made later in the paper above cited (1. c, p. 

 376, where, in some unaccountable way my former division of 

 the 'North Temperate Realm' into 'Subregions' was wholly 

 overlooked !). Dr. Packard, in his otherwise excellent 'Zoo- 

 geographical Map of North America,' failed, however, to recog- 

 nize the southward extension of the Cold Temperate Subregion 

 along the principal mountain systems of the continent. 



Dr. Merriam in 1890 1 again set off the Cold Temperate Sub- 

 region, under the name 'Boreal Province,' and mapped in detail 

 its southern prolongations into the mountainous parts of the Warm 

 Temperate. The Warm Temperate Subregion was also recog- 

 nized as a contrasting region of coordinate rank, under the 

 designation 'Sonoran Province,' while the old 'Eastern,' 'Middle,' 

 and 'Western' Provinces were properly repudiated as having no 

 basis in nature. Particularly is this the case in respect to the 

 Central Province, of which Dr. Merriam observes: ''The region 

 almost universally recognized by recent writers as the 'Central 

 Province' is made up of the Great Plains, the Rocky Mountains 

 and the Great Basin. A critical study of the life of the Rocky 

 Mountains has shown it to consist of a southward extension of the 

 Boreal Province, with an admixture of southern forms resulting 

 from an intrusion or overlapping of representatives of the Sonoran 

 Province, some of which, from long residence in the region, have 

 undergone enough modification to be recognized as distinct sub- 

 species or even species. A similar analysis of the Great Plains 

 and Great Basin has shown them to consist of northward exten- ' 

 sions of the Sonoran Province, somewhat mixed with the southern- 

 most fauna and flora of the Boreal Province. Thus the whole of 

 the so-called 'Great Central Province' disappears. 



"This explains a multitude of facts that are utterly incompre- 

 hensible under the commonly-accepted zoological divisions of the 

 country. These facts relate particularly to the distribution of 

 species about the northern boundaries of the supposed Central 

 and Pacific Provinces, and to the dilemma we find ourselves in 

 when attempting to account for the origin of so many primary 



1 N. Am. Fauna, No. 3, Sept. 1890, pp. 24-26, and map 5; see also Proc. Biol. Soc. 

 Washington, VII, 1892, pp. 21-40, and accompanying map. 



