MONTANA SHELLS. 259 



animals, but will also by its growth supply oxygen for their needs. 1 

 discover that pond scum may be kept growing all winter if placed in a 

 south or west window for sunlight. Of course, water species may be 

 kept in winter, when it will probably be found impossible to keep land 

 species. In spring and summer the land snails may be kept in a suitable 

 cage, and with a small amount of care and trouble in supplying food and 

 in keeping the cage clean they will amply repay for the trouble. Pupils 

 will find them interesting, and with a few suggestions will be able to make 

 many valuable observations, and thus get true nature study lessons, a 

 study of the living specimen whose habits and natural peculiarities may 

 be known first hand. 



The land snail most aboundant in the state is Pyramidula strigosa 

 Gld. It is found abundantly west of the Rocky mountains at all altitudes 

 from the lowest elevations to 9,000 feet. The shells found may easily 

 be referred to several varieties. Pigure 23 shows their general appear- 

 ance. The shell is rather thick and heavy, recognized by two dark 

 bands, one of which extends into the spire for several whorls. Closely 

 related to it, and often associated with it, is Pyramidula solitaria Say, 

 but the latter is more earthy, with darker color, a trifle flatter, and with 

 broader bands, not extending into the spire. Solitaria is less common, 

 and is not yet reported from east of the range. 



Pyramidula strigosa has been taken by us abundantly in the western 

 part of the state. It has been found on the slopes of many mountain 

 ranges in the state. It has been taken as far east as Lewistown. It is 

 a Rocky mountain species, and is so variable that conchologists despair 

 of bringing the numerous subspecies and varieties into systematic rela- 

 tions which will be satisfactory. At two places in the Mission range, 

 Sinyaleamin and McDonald mountains, it has been found at high alti- 

 tudes, as explained in "A Biological Reconnoissance in the Vicinity of 

 Flathead Lake." The lower snails are large and fine looking. The 

 higher ones are very small, greatly reduced in size, and have very hard 

 conditions to fight against in the struggle for a living. While the species 

 is apparently of western origin, its presence at Lewistown shows that it 

 has crossed the range, and is slowly making its way eastward. This is 

 the second species, according to our studies, that has crossed the main 

 Rockies, the other being a dragonfly. As there are seven species found 

 in the state on both sides of the main range it is apparent that they have 

 crossed the range in some way. As P. strigosa has been found at eleva- 

 tions up to 9,000 feet it seems reasonable to suppose that it was not car- 

 ried over by some larger bird or animal, but crossed over by its own 

 wanderings. 



Several hundred duplicates have been collected, and two or three 

 will be sent to any teacher of nature study, so long as they last, if postage 

 accompanies the request for them. 



It is needless, in this lecture, to atempt giving a list of the sixty 

 species found in the state, twenty-five of which have been found west of 

 the range, with forty-two from the east side. A list may be found in 

 Bulletin University of Montana, Biological Series No. 3, pp. 170-174. 

 Teachers who wish shells identified may send them to the writer, who will 



