3) 
average amount of moisture varies in portions of each life zone it 
follows that the distribution of life is not equal throughout a life 
zone. ‘l’o give expression to the effects of the varying amounts of 
moisture in life realms and life zones they are divided in sections 
of variable size called regions, sub-regions and provinces. ‘That part 
of the North ‘temperate Life Realm on this continent is known as 
the North American Region. ‘That part of this region in western 
North America having a small annual rainfall is known as the 
‘Arid Sub-Region, and the part near the sea having a large rainfall is 
the Pacific Coast Sub-Region. ‘The Arid Sub-Region has been 
divided into two provinces: the Sonoran Province consisting of that 
part in the Lower Austral and Sub-Tropical Zones ; and the Campes- 
trian, consisting of that part in the Upper Austral and ‘Transition 
Zones. 
I propose further subdividing the life areas of California into 
‘aunas, to consist of areas of nearly equal temperature, moisture 
and soii, and the therefore a nearly homogeneous local assemblage 
of life forms. ‘These will not be equal in either size or value, and 
are intended only to facilitate the study of distribution of species in 
California. ‘The boundaries of Life Zones and Faunas as indicated 
on the accompanying map are only provisional; further study will 
necessitate numerous changes. 
The Californian Arctic Fauna is that part of the Arctic Life Zone 
in California. A few species of plants constitute the only peculiarly 
Arctic life in California, as the areas are so small that animal life of 
strictly Arctic species has disappeared, with the possible exception of 
insects. 
The Boreal Zone is forested nearly throughout its extent in Cali- 
fornia. ‘The principal forest trees are the Foxtail Pine, White-barked 
Pine, Mountain Pine, Tamarack Pine, and Red Fir. The Californian 
mammals peculiar to this zone are the Gray-headed Pika, Mountain 
Beaver, Yellow-bellied Marmot, Belding Ground Squirrel, Alpine, 
Sierra Nevada and Alpine Chipmunks, Californian Pine Squirrel, 
Black Fox, Wolverine, Pine Marten and Ermine. Some of the birds 
breeding principally or exclusively in this zone are Sooty Grouse, 
White-headed Woodpecker, Williamson Woodpecker, Western Night- 
hawk, Calliope Hummingbird, Olive-sided Flycatcher Gray-eared 
Finch, White-crowned Sparrow, Lincoln Sparrow, Thick-billed Spar- 
row, Green -tailed Towhee, Audubon Warbler and Black-throated Gray 
