NORTH AND SOUTH. 371 



straggle along tlie southern edge of the inhospitable Barren 

 Grounds of arctic America a treeless, blizzard-swept waste of 

 mosses and saxifrages, the home of the wolf, the musk ox, and 

 the Barren Ground caribou, stretching away to the shores of the 

 Arctic Ocean. 



Zoologists recognize several well-defined regions within these 

 life zones, each of which is characterized by some forms of rep- 

 tiles, birds, and mammals that do not range or breed beyond its 

 limits. These geographical life areas have received the name of 

 faunas. In the eastern United States four such regions are rec- 

 ognized and are known as the Canadian, Alleghanian, Carolin- 

 ian, and Louisianian faunas. The Canadian fauna belongs to 

 the boreal region. It is characterized by certain species of mam- 

 mals that do not range south of it, as the moose, caribou, and 

 wolverine, and by certain birds that breed within its borders. 

 Among these latter are the well-known snowbird, several species 

 of wood warblers, the winter wren, and the hermit thrush. This 

 fauna extends southward to Georgia along the hemlock-crowned 

 crests of the Appalachians, where the altitude produces condi- 

 tions similar to those prevailing in the coniferous forests of the 

 boreal zone to the north. Through the deep, cool shades of these 

 hemlock woods floats the song of the hermit thrush a vesper 

 strain that falls on the sense like the tinkling of some far-off, 

 sweet-toned bell, rising and swelling in an amplitude of liquid 

 melody that fills the twilit aisles and dies away in still solitudes. 

 The pleasing song of the snowbird breaks upon the forest still- 

 ness, quite different from its sharp, clicking notes so familiar in 

 our winter walks about home. Along the brawling mountain 

 brooks and trout streams of the AUeghanies the water thrush, 

 with oddly jerking motions, bobs up and down on the rocks, and 

 the winter wren flits about the windfalls or steals away from its 

 nest, that is hidden under the gnarled roots of some old stump 

 that overhangs the bank. To an ornithologist these and other 

 features indicate a decided Canadian tinge in the summer bird 

 fauna of the higher ranges from the Catskills to Georgia. 



The so-called Alleghanian fauna of the eastern transition zone 

 includes all the more familiar species of birds, reptiles, and mam- 

 mals inhabiting the New England and Middle States and the 

 lower ranges of the Appalachian highland to the south. Its chief 

 characteristic is a mingling of the life of the other two zones 

 the boreal and the austral. Such decidedly northern forms as the 

 bay lynx or catamount, the red squirrel, porcupine, woodchuck, 

 chipmunk, jumping mouse, and certain other mammals find their 

 ranges restricted along the southern boundary of this fauna. A 

 number of familiar birds, as the brown thrasher, scarlet tanager, 

 bluebird, house wren, chewink, indigo bird, meadow lark, the 



