OCT., 1900.] FAUNAL DISTKICTS. 11 



{Oms dalll). Although the lake widens slightly at its lower end, its 

 outlet is a narrow stream about 3 miles long, called Caribou Cross- 

 ing- (Plate II, fig. 2), on the north side of which is an open, grassy 

 swamp })ordered ]jy willow thickets. This low country, though very 

 limited and not extending to the next lake, affords a breeding place 

 for a few mammals and birds not found about Bennett. 



Lake Tagish, which receives the waters of Bennett through Caribou 

 Crossing, is like Bennett in character, though not so closely walled, 

 and is characterized by practically the same plants and animals. The 

 surrounding mountains are covered with dense forests, which in many 

 places are almost impenetrable. 



Connected with Lake Tagish by a short, narrow stream, known as 

 Six-Mile River, is Lake Marsh, a long shallow lake on each side of 

 which extends low country, with rolling hills farther back. The valley 

 widens here quite appreciably, and the open country is like that at 

 Caribou Crossing. On the east side are sedgy l^ogs surrounded by 

 willow thickets, and in many places a wide margin of beautiful green 

 sedge meets the edge of the water. Rocky shores are found at some 

 points on the northwest side, but in general the country is low and 

 moist, in marked contrast to that about Bennett and Tagish. The 

 mountain animals of those lakes are of course absent, and the bird life 

 i.s also somewhat different. 



Fifty-Mile River, into which the Yukon waters proceed from Lake 

 Marsh, is rather narrow, and for a short distance at White Horse Rap- 

 ids very swift. Its banks are chiefly abrupt bluffs of sandy clay (from 

 50 to 100 feet high) but at Miles Canyon it is confined between walls 

 of basalt. Below the rapids the stream widens somewhat and the higli 

 banks become less frequent, often being replaced l^y low ones thickly 

 grown with willows. The timber is somewhat scattered, and on the 

 rolling hills back from the river bare granite spaces may be frequently 

 seen. At the head of Fifty-Mile River, we first met with birch trees 

 {Bettda 2)a2)yrifera f)^ and from that time on they were seen daily. 

 They do not grow to large size — trees more than 8 inches in diame- 

 ter were seldom seen. Several small streams flow into Fifty-Mile 

 River, which favor the growth of thickets of alders along their )>anks 

 and large clumps of willows about their mouths. The little l)oreal 

 sagebrush {Artemisia Jrigida) grows abundantly on the warm exposed 

 slopes that occasionally alternate with the sandy 1)luffs. Lodgepole 

 pines are also abundant and f requentl}' occupy large areas to the exclu- 

 sion of all other trees. Spruce and poplar, however, are still the strong- 

 est elements in the forest. 



From Fifty-Mile River we enter Lake Lebarge, the last and largest 

 of the lakes. All abovit its clear, cold waters are low granite moun- 

 tains (Plate III, fig. 1). Occasionally patches of heavy spruce forest 

 are found near the Avater, l)ut in man}^ places clift's rise al)ruptly from 



