104 BULLETIN UNIVERSITY OF MONTANA 
the lakes and rivers, and being able to live on the mountain sides during 
the damp spring months, in summer disappearing from sight until the fol« 
lowing spring. As the ascent was made and the struggle became fiercer 
the size of the shells became reduced, this form being much smaller than 
the variety cooperi. But still others ascended to higher realms and are 
now found on the highest and bleakest of rocky slopes. This P. strigOsa 
var. alpina is no doubt the result of this gradual ascent. In size it is 
small, being really diminutive. The struggle is great. Food is scarce. 
‘To support so large a body as the small form lower down, or the ordinary. 
specimen at the lake or creek, is impossible. Consequently, there has 
been a change in structure to accommodate the changed conditions, and 
the shell is much reduced in size. The form, cooperi, has not been found 
by the writer above 4,000 feet. The small variety is found from 5,000 feet 
to 7,000 feet in the west, and higher in the east. The diminutive variety 
has been taken on this occasion at an altitude of 8,500 feet and from that 
nearly to the top. The same diminutive shell was later taken on Mc- 
Donald peak at an altitude of 8,000 feet to 9,000 feet. 
Plate XXVII will give the reader a better idea of the size and rela- 
tionships of the shells before mentioned than can be obtained from a de- 
scription. 
The summit was reached at 4:15 in the afternoon. It was completely 
bare of vegetation save for one little straggling specimen on the west- 
ern edge, catching the rays of the sun, and not sufficiently far along in 
growth to make a determination. The aneroid registered 9,150 feet. Al- 
though the sky was cloudless a few pellets of snow came from some placa 
and struck us in the face. At our feet was an immense snow drift on 
which the camera was planted and which was covered with goat 
tracks. 
The sight was fine. No one can tell the glories, beauties, or de- 
pict the awfulness of the view from one of the heights of the Mission 
range. To the west is the twin peak of the one we have ascended, show- 
ing beautifully the stratification, and the formation of the mountain. Be, 
yond this peak the mountain drops almost abruptly to the plain. To the 
north the range appears as one vast jumble of peaks and ridges, though 
of course there is order in it all. Reference is made to the impression. 
To the east the Jocko peaks rise abruptly from the snow fields, old snags 
that appear incapable of being ascended. A view of these is given in 
Plate XXI. Between Sinyaleamin and the Jocko peaks is a large gla- 
ciated region, no doubt the former ice region supplying the material for 
the moraine at Sinyaleamin lake, or the lakes toward the east. At the 
foot of the old Jocko crag is a small lake, filled with slush snow and ice, 
as viewed from our distance, and which has been christened Snow lake in 
consequence. This Snow lake is in the drainage of Sinyaleamin lake, 
the waters entering Snow lake, overflowing, passing down over the rapids 
into Sinyaleamin lake, and on to Mission creek. To the south Mount 
Lo Lo, in the Bitter Root range, may be seen 75 miles away. The Bitter 
Root range, Cabinet and Swan ranges, the Mission range in the fore- 
ground, the Kootenais and the Rockies, make a grand and beautiful pan- 
orama. Thirty miles to the north may be seen Flathead lake, blue as the 
