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 f/ere 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-j 

 sand specimens from this field alone. 



The camp was made primarily to secure further information relative 

 to P. eirodi 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. eirodi was at home. Large 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. eirodi 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 eirodi and strigosa. The shell 

 is of a young specimen, less than half grown. 



P. eirodi 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. eirodi and its home. 



