52 



NORTH AMERICAN TAUNA. 



[NO. jT. 



entire area, exclusive of the alpine summits of the mountains. The 

 Canadian of the Liarcl Valley is probably continuous, or nearly so, 

 by way of the yalleys of the Frances and Pelly, with the Canadian 

 on the Yukon. 



CANADIAN ZONE. 



The Canadian zone includes all the countr}^ to the southward of the 

 line just defined. It thus comprises the Athabaska and Peace Eiver 

 yalle^'S, the Slave Eiver Valley, and all the country stretching south- 

 ward from Great Slave Lake, the upper Mackenzie, and the lower 

 Liard. Along the Mackenzie it sends a narrow tongue northward 

 through three degrees of latitude. This strip merely represents the 

 influence exerted on the fauna and flora by the warmer waters and 

 climate of the Liard and by the broad stretch of low country to the 

 southward. 



Among the birds limited in their northward range by the upper 

 border of the Canadian zone and which are more or less character- 

 istic of it, are Picoides arcticus, Bonasa u. umheUoides, XuttaUornis 

 horealis^ Emj>idonax minimus, Zonotrichia alhicollis^ SpizeUa p. ari- 

 zorue^ Jlelospiza liiicolni and M. georgiana, Lanivireo solitarius^ 

 Flelminthophila celata and FI. peregrina^ Dendroica magnolia^ 

 Hylocichla u. sioainsoivL and H. g. pallasi. 



The northern border of the Canadian zone in the Mackenzie region 

 limits the successful cultivation of barley, potatoes, and the more 

 hardy root crops, although with special care most of them are raised 

 in certain favored localities in the southern part of the Hudsonian. 

 Even in the Canadian, however, an occasional failure occurs, in the 

 case of the less hardy crops, because of the occurrence of uiuisually 

 late spring or early autumn frosts. In most parts of the Peace 

 Eiver Valley, and even in the lower Liard Valley, Avheat is a success- 

 ful crop. Peas, potatoes, radishes, turnips, beets, carrots, cabbages, 

 lettuce, and onions are raised with a considerable degree of success 

 as far north as Fort Norman, near latitude 65°. near the northern 

 extremity of the Canadian strip. Nearly or all of these meet with a 

 fair amount of success at Fort Eae and also at Fort Good Hope, in 

 the lower Hudsonian, but at Fort Eae the situation is especially 

 favorable as regards slope exposure, and the permanent frost, which 

 remains near the surface in most parts of the Hudsonian, probably 

 retreats to a much lower depth. At Fort Good Hope the almost 

 continuous sunlight of summer probably compensates in part for its 

 extreme northern position. 



