26 NORTH AMERICAN FAUNA. [xo 16. 
and cliffs, but for some unaccountable reason even rarer than the cony, 
is the bushy-tailed wood rat or pack rat (Neotomea cinerea), which, if 
my memory serves me correctly, is less common on Shasta than on any 
other mountain I have visited in the West. The mountain chipmunk 
(Eutamias scene) and golden ground squirrel (Callospermophilus chryso- 
deirus) inhabit the tongues of pines on the ridges, and not infrequently 
live in burrows among the bare rocks. Marmots, it is safe to assert, are 
altogether absent. We completely encircled the peak in the neighbor- 
hood of timberline, and examined innumerable Jedges and rock slides, 
such as on other mountains are inhabited by marmots, but without find- 
ing so much as a track or sign or even a bleached bone to indicate that 
any member of the genus -irctomys bad ever inhabited Shasta. In 
former days the bighorn (Oris canadensis) was common here, but now 
the occasional fragment of a skull or the scattered parts of a skeleton 
areallthatremain. In fall the old bucks of the Columbia black-tail deer 
wander up on the higher ridges. Here and there, particularly in the 
shelter of the prostrate white-bark pines, tracks and dung of rabbits 
were seen, butin spite of all our efforts no member of the party succeeded 
in finding a rabbit on the mountain. The species is probably the Sierra 
rabbit (Lepus hlumathensix), though from the large size of some of the 
dung pellets I was inclined to suspect the presence of Lepus campestris. 
AVALANCHES, 
During the loosening of the snow in spring, avalanches must be very 
common on the higher slopes, and it is probable that they exert a 
controling influence in determining the timber areas above the limit of 
continuous forest. Nothing forces itself on the observation more firmly 
than the peculiar way in which the white-bark pines are restricted to 
the Jong radiating ridges where they form narrow tongues, separated 
by broad intervals of steep slopes and basin-shaped valleys. While it 
might be hazardous to assume that the absence of trees from these 
extensive slopes and basins is due mainly to avalanches, the fact 
remains that the tracts they occupy along the tops and upper slopes 
of the ridges are entirely out of reach of these resistless engines of 
destruction. 
Now aud then, however, an avalanche, taking an unusual course, 
reaches the outskirts of one of these tongues of alpine pines and 
snatches up and carries below all that Jie within its path. This is 
evident from the weathered trunks and roots often found at the bot- 
toms of slopes where trees have never grown, 
The most conspicuous path of a recent avalanche observed is on Cold 
Creek, between the deep canyons of Mud and Ash creeks (fig. 13). Here 
an avalanche of unusual size must have shot down the higher slopes 
until it reached the upper edge of the continuous forest of Shasta firs, 
where, instead of stopping, it cut a broad swath through the huge 
trees, tearing them up by the roots or snapping them off and carrying 
