NEARCTIC REGION (front Gk. rlos, DPW ± dphrocos, arIrlik0.s, arctic, northertil. A region in zoilgeography including the entire con tinent of North Anieriea, except the hot coast. land: of Mexico. It is a part of Aretogwa, or the Holaretie llegion, in the view of those who regard the Northern Hemisphere as at 1111i1 in hilt in the scheme of Sclater and Wallace it is one of 1110 six primary regions, co ordinate with the Palearet ie Province. (See i)is' 11r ANINtm.s, Zobarographiettl Map.) Of further interest here are the subdivisions or local faunal area: that have been distinguished.
The earliest attempt at this set apart three re gions—an 'Eastern,' from the Atlantic to the plains; a 'Central,' inelnding the dry interior plains; and a 'Western,' the Paeitie Slope. As early as 1854 Louis Agassiz stated that the east ern half of the continent contained three faunas: a northern, which he called •Canadian;' a middle (Great Lakes to the latitude of Ken tucky), which he called 'Alleghenian:' and a southern or 'Louisianian.' Later writers, es pecially Allen, dealing mainly with birds. made eight zones in succession from north to south—Arctic, Hudsonian, Cana dia ghanian, Carolinian. Louisianian. Floridian, and Antillean. Ornithologists use this classification cast of the Mississippi Liver. Sub sequently Merriam announced the opinion that there was no reason for recognizing a 'C'entral Province,' and that too much stress had been laid upon the dissimilarities between East ern and Western animals. Tie asserted the
view that only two primary subdivisions of the Nearetic Region should be 1110 de—a 'Boreal' province and a 'Sonoran' province. The former stretches from New England and the Great Lakes northwest across Canada to Alaska, and sends down long arms along the heights of the Alle ghanies and the Rocky Mountains, and along the Pacific Coast, whose fauna is a mingled one. Everything south of this is 'Sonoran.' embracing nearly all the United States, a great area of the plains of Northwestern Canada, and all of Mex ico except the low tropical coast-lands. These generalizations, however, have not been universal ly accepted. most critics objecting that too high rank has been accorded to the 'Sonoran' region, whose boundaries are regarded as too indefinite to entitle it to be differentiated and outlined as )Ierriam proposed in his "Biological Survey of the San Francisco Mountain Region," in Xorth HI crican Fauna, (Washington, 1890). The question of the subdivision of the Nearctic Re gion therefore remains open.