114 BULLETIN UNIVERSITY OF MONTANA 



something like twelve or fifteen miles. On the assumption that the 

 shells would start from the water course, and possibly follow the ridge on 

 the shady and damp side, they must have taken entirely different routes 

 in ascending the two peaks. They were found abundantly on McDonald 

 peak at the altitude 7,800 feet to about 8,500 feet. It is worthy of note 

 that the shells seem to begin and end rather abruptly. When first 

 found, on either mountain, they were found in considerable numbers. 

 The high summits of McDonald are so steep, and the broken rocks so large 

 In size, that there seems a limit to the range of the shell on McDonald. 

 From our observations it appears that on the south side of Lake Mc- 

 Donald thre is a break from the slopes immediately above the lake, with 

 altitude about 3,400 feet, to 7,800 feet, in which no strigosa have been 

 found. They are probably there, but sparingly, since diligent search 

 was made during the ascent. On the other bank, however, the northern 

 slope, strigosa has been taken from the lake to altitude 7,500 feet, and 

 continuously. Moreover, the shells taken at the high altitude on the 

 north slope are many times the size of those taken on the opposite mount- 

 ain. The locality in which the shells were taken on McDonald is on a 

 ridge facing the west, bare of trees and other shelter, wind-swept, and 

 storm-swept. On the north, on Teton mountain, the ridge faces the west, 

 but is well wooded and protected, and apparently retains moisture much 

 longer. To conchologists and others the wanderings of this shell will 

 be of much interest, and the description has been given in some detail be- 

 cause of that interest. 



A good series of Poiygyra tawnsendiana, var. ptycophora was secur- 

 ed. The underbrush was so dense that it was necessarry to crawl on 

 hands and knees most of the time among the shrubs and small trees. By 

 digging in dead logs, overturning decayed stumps and branches and 

 pulling apart dead leaves a good series was obtained, but at the sacrifice 

 of clothing and flesh. 



Of these three species many were found eaten by squirrels. These 

 were carefully preserved, and examination made of the method of proce- 

 dure. The usual method was to break the shell at the apex of the spire, 

 making a good sized opening. Through this the animal was drawn and 

 no doubt afterwards devoured. A few openings were made at other 

 places, and sometimes at very unfavorable places, due no doubt to lack 

 of experience on the part of the enemy. Of the species P. strigosa, var. 

 cooper! fifty were found thus broken into. Of P. solitaria four or five more 

 than of cooperi, while P. townsendiana, var. ptycophora had but two thus 

 eaten. As these latter much more resemble the surroundings than do 

 the striped Pyramiduias this is not surprising, and is a good illustration 

 of protection. 



On the talus north of the lake the bleached remains of a hitherto new 

 shell were lying abundantly on the rocks. During the short stay at tha 

 lake in July, 1899, some forty specimens of this shell were secured, 

 Pilsbury described it as a new species in Nautilus, Vol. XIV., P. 

 40. The species is shown in Plate XXXII. It certainly is a species as 

 distinct as many other described species, and certainly is unlike any other 

 shell so far described in many respects. Whether or not intermediate 



