4 University of California Publications in Zoology. |Vou-5 
largely above the 9000-foot contour. It is far less in extent than 
any of the others because of the limited area of so great an 
altitude. A number of Boreal meadows occur as islands, sur- 
rounded by high Transition, in the vicinity of Bluff lake, 7500 
feet altitude, and alone the ridge eastward to Sugarloaf moun- 
tain. This peak is capped by at least one and one-half square 
miles of Boreal, mostly on its northern slope. There are no other 
Boreal areas that I know of north of the valley of the upper 
Santa Ana. But south of this east-west depression lies the lofty 
San Bernardino ridge, with San Bernardino peak, 10,600 feet 
altitude, at the west end, and San Gorgonio peak, 11,485 feet 
altitude, at the east end. This ridge is covered by fully twenty 
square miles of the Boreal zone. 
As to the divisions of Boreal into Canadian, Hudsonian, and 
Alpine-Aretice, there are plant representatives of each of these 
zones, the Canadian being best characterized and of largest ex- 
tent. But I could not decide upon a single species of animal 
which could be considered separately characteristic of any one 
of these Boreal divisions. An upper and a lower division of the 
Transition zone seemed to me far more easily distinguishable on 
this mountain group, than Canadian from Hudsonian or the latter 
from Alpine-Aretic. As intimated above, there are no purely 
Hudsonian animals. Even the Canadian, as far as animals are 
concerned, has but very few preponderant representatives. Such 
as it has are: Lincoln sparrow, Mexican erossbill, Williamson 
sapsucker (occurs also in high Transition), Clarke nuteracker (is 
a constant resident on certain ranges of southern California where 
only Transition-zone plants occur), ashy kinglet (oceurs also in 
upper Transition), and Microtus mordax bernardinus. A good 
many others run up from upper or lower Transition through 
Boreal nearly to the limit of trees. On account of this difficulty 
of distinguishing the three divisions of the Boreal zone, I here- 
after consider them as grouped together into simply “‘ Boreal.”’ 
In the descriptions of localities beyond, I have much more to 
say as regards the local extent of certain of the zones. The gen- 
eral subject of zonal distribution has been thoroughly discussed 
by Merriam in his ‘‘Results of a Biological Survey of Mount 
Shasta, California’? (North American Fauna No. 16, 1899), 
