116 BULLETIN UNIVERSITY OF MONTANA 
in the last of June. It was the rainy season. In three weeks there 
were but three or four days of sunshine. While this bad weather was 
hard on those living out, as we were obliged to do, it was the best time of 
the year for collecting . One day while at this lake the rain came down 
almost the entire day. It was just such a day as would be good for land 
shell collecting, and rigged out in gum boots and a slicker the writer spent 
the greater part of the day crawling through the wet underbrush in search 
of shells. They were found in great abundance. P. strigosa and P. 
solitaria were out in great numbers. It is no exaggerations to say that 
if one had desired to do so he could have secured a peck of these two 
species. With them was now and then found a Polygyra townsendiana, 
var. ptycophora, but they were in no great abundance. Considering the 
small territory examined the number of shells to be had of these two spe. 
cies in the region of McDonald lake is very great. As it is the collection 
taken and brought to the University of Montana was more than a thou, 
sand specimens from this field alone. 
The camp was made primarily to secure further information relative 
to P. elrodi Pils. Immediately after a rain the rock talus on the north 
bank of the lake was examined. The rocks were very slippery, the grade 
steep, and the bushes dripping with moisture. Rain fell a portion of the 
time. But P. elrodi was at home. lLarge and small, they were every- 
where in abundance. In 1899 but a few bleached shells were found on 
the exposed rocks. In 1900 a much larger number of bleached shells 
was found, together with a few live ones. They were also followed up 
the mountain slope about two thousand feet. But during the camp of 
1901 large numbers, of all sizes and apparently all ages, were taken. They 
were crawling over the rocks in plain sight, though almost invisible save 
by close scrutiny, owing to their resemblance in color to the rocks, and 
were traced up the mountain to an altitude of over 7,500 feet. At this 
altitude the dead shells with occasional live ones, were still abundant. 
As we had started up the mountain in the afternoon it was impossible to 
go farther that day, and the return was made to camp, with plans for 
ascent to the end of the shell region. That night a storm prevailed, and 
we concluded from indications we would fare better out of the hills, and 
got out, none too soon. The next morning the hills were white with new 
snow, remaining so for a long time. 
In making this search up the mountain a shell was found which is 
undoubtedly a hybrid between P. elrodi and P. solitaria or P. strigosa. 
It has the form and sculpturing of the former, and the characteristic band 
markings of one or the other of the latter. Which of the latter it is diffi- 
cult to determine. But as strigosa was much more abundant along the 
ridge than solitaria the hybrid is probably elrodi and strigosa. The shell 
is of a young specimen, less than half grown. 
P. elrodi is not the only shell that made the ascent of the mountain. 
Associated with it, even to the highest point, P. strigosa, and P. solitaria, 
in varying numbers, were taken. The result, is a fine series, from alti- 
tudes from 3,300 feet to 7,500, which will afford material for working out 
the results of altitude. 
It is not inappropriate to quote the following paragraph in reference 
to P. elrodi and its home. 
