THE BOREAL FAUNA AND FLORA OF SHASTA CONTRASTED 
WITH CORRESPONDING FAUNAS AND FLORAS OF THE SIERRA 
AND THE CASCADES. 
In considering the relations of the boreal faunas and floras of Shasta 
to those of other parts of the Sierra-Cascade system it is necessary at 
the outset to have a clear conception not only of the extent of the 
range as a whole, but also of the number and magnitude of the breaks 
or gaps in the continuity of its boreal fauna and flora. The Cascade 
Range enters the State of Washington from British Columbia in lati- 
tude £9° and pushes southward completely across Washington and 
Oregon; its continuation, the Sierra Nevada, traverses California 
for a distance of 500 miles, ending a little south of Mount Whitney, in 
about latitude 36°, The Cascade-Sierra system, therefore, extends over 
13 degrees of latitude, and has a total length of fully 1,000 miles. For the 
whole of this distance it rises abruptly from a low region, whose faunas 
and floras are in the southern part Sonoran, in the northern part Tran- 
sition. The field work of the Biological Survey has shown that the 
narrow boreal band which occupies tle higher parts of the range is not 
continuous, but is interrupted by four important gaps, through which 
Transition zone species pass freely in broad belts from one side to the 
other. These gaps, begining at the north, are: 
(1) The Columbia Gap, or gorge of the Columbia River, on the bound- 
ary between Washington and Oregon, where the breadth of the Tran- 
sition zone seems to be less than 50 miles.! 
(2) The Klamath Gap, on the boundary between Oregon and Califor- 
nia, extending from a little south of Mount Pitt in Oregon to Mount 
Shasta in California, a distance of about 50 miles. This interval is 
interrupted by o1e or two detached groups of low mountains on the 
California side, and by long ridges on both sides, whose summits are 
inhabited by boreal species, materially decreasing the actual breadth 
of the gap. 
(3) The Pitt River Gap, between Mounts Shasta and Lassen in north- 
ern California. The breadth of the Transition zone here is about 60 
niles. 
‘Although not bearing on the fauna of Shasta, it is interesting to note, in connec- 
tion with the effects of the Columbia River Gap, that a number of species chiurac- 
teristic of the northern Cascades, in the State of Washington, do not occur in the 
southern Cascades, in Oregon. Among the mammals the most notable species of 
this kind are Arctomys caligatus, Callospermophilus saturatus, Evotomys gapperi satu- 
ratus, Oreamnos montanus, Peromyscus oreas, Putorius washingtoni, Zapus trinotatus. 
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