Hudsonian, Canadian, Transition, Upper Sonoran, Lower Sonoran, and Tropical. East of the hundredth meridian, which, broadly speaking, is the dividing line between the eastern or humid and western or arid sections, the Austral zone is known as Austral rather than Sonoran, and divided into Alleghanian, Carolinian, and Austroriparian Faunas.The Alpine Zone lies above the limit of trees, and is characterized by dwarf shrubs and plants, the polar bear, arctic fox, reindeer, the snow bunting, snowy owl, ptarmigan, pipit, and leucosticte. The Hudsonian Zone is marked by dwarfed timber along "the northern or higher parts of the great transcontinental coniferous forest, . . . stretching from Labrador to Alaska. It is inhabited by the wolverine, woodland caribou, moose, great northern shrike, pine bullfinch, and white-winged crossbill." 2 On Mt. Shasta its only trees are the black alpine hemlock and white-barked pine, its characteristic mammal is the cony (Ochotona), and its characteristic bird the Clarke crow. It is also frequented by the sooty grouse, western goshawk, Williamson sapsucker, rufous hummingbird, Oregon jay.pine siskin, junco, Audubon and hermit warblers, creeper, redbreasted nuthatch, kinglets, and solitaire. 3 1 Merriam's " Laws of Temperature Control of the Geographic Distribution of Terrestrial Animals and Plants," Xadonal Geoara/>hic Mnyazinc, vi. 229-23S.2 Merriam, C. Hart, "Life Zones and Crop Zones of the United States," Bull. No. 10, Kiologicnl Sun-i'ii ; " Geographic Distribution of Animals and Plants in North America," Yearbook of the U. 8. Department of Agriculture, 1SD4.