Migrations of North American Birds. 267 



a trend westward in British America as to reach and even cross 

 the Rocky Mountains, we shall be greatly aided by the examina- 

 tion of Prof. Guyot's Wall-Map of North America. On this 

 map the country not exceeding 800 feet in height is coloured 

 green ; and this portion is almost exactly coincident with the 

 limits of the eastern province just defined — reaching west of the 

 Mississippi almost to the edge of the fertile plains (the true 

 zoological boundary), passing up the Mississippi via St. Paul to 

 the Winnipeg valley, involving the whole shores of Hudson's 

 Bay, thence in a north-westerly direction, a little south of Slave 

 Lake to the foot of the Rocky Mountains, and north to the 

 Arctic Ocean on both sides of the Mackenzie. Within this vast 

 country are " islands " of more elevated land, the whole Appa- 

 lachian range, from New Brunswick to Central Georgia and 

 Alabama, the height of land between Hudson's Bay and the 

 St. Lawrence system of waters (nearly parallel with the latter), 

 the plateau of Iowa and Northern Wisconsin, and that east of 

 Slave Lake* &c. being more or less completely encircled by the 

 lower level referred to. The highlands within this region have 

 to a certain extent a peculiar fauna, chai'acterized by the presence 

 of such species, to a considerable degree even in summer, as 

 Junco hyemalis, Perisoreus canadensis, Chrysomitris pinus, Cur- 

 virostra americana (more rarely C. leucoptera) , Pinicola canaden- 

 sis, &c., most of which are known to breed in the high mountain- 

 region of Georgia. These highlands do not, however, materially 

 alter the summer distribution of our birds, especially in the 

 interior ; and there is no physical obstacle, not even that of tem- 

 perature, to interrupt or affect their passage by way of Rupert's 

 land to the shores of the Arctic Ocean f. 



* This region, bounded west by Coppermine River, Slave, Athabasca, 

 and WoUastou Lcikes, and south by Churchill Eiver, is known as the 

 Barren Grounds of Arctic America, and is a great granitic or azoic region, 

 more or less barren of vegetation, destitute of large trees, and having few 

 inhabitants. It is, however, the especial home of the Musk-Ox, the 

 Barren-Ground or small Reindeer, the Barren-Ground Bear, the Polar 

 Hare, and other species. 



t The Appalachian Region towards the north and north-east passes 

 into a well-marked subdivision, called by Prof. Verrill, in his paper on the 

 birds of Norway, Maine, the '' Canadian." This he correctly charac- 



