2 THE NAUTILUS. 



later an ascent was made of McDonald's Peak, fifteen miles furtiier 

 north in the range. At height of 7,500 feet a hunt was made for 

 the shells, and the first were found at 7,800 feet, continuing until 

 nearly 8,500, when the rocks were so large and so steep it was useless 

 to search for them. 



Finding specimens on the high slopes of two peaks in the same 

 range, at about the same altitude in each case, seems to indicate that 

 they are not found lower. At this altitude the summer is short. 

 The months of June, July, August, with possibly a little of Sej)tem- 

 ber, is the period of activity. Snow was not far from the specimens 

 found. In one case, only a few feet from the shells was a large snow 

 bank. 



The slope on McDonald on which they were found lies to the 

 west. The shells here would receive tlie sun early in the forenoon, 

 and the last rays as the sun sank behind the hills would strike the 

 ridge on which they were living. The conditions were much more 

 favorable than on Sinyaleamin peak. The snow melts sooner, the 

 ridge is broader with more pulverized rock and more vegetation. 

 The absence of snow tempers the winds. The altitude is a few hun- 

 dred feet lower, which might make a difference. 



Search was made for an hour or more for the shells. A large shell 

 vial was filled, a couple of dozen live ones being placed in a separate 

 vial. Living specimens on both McDonald and Sinyaleamin peaks 

 were proof that they live there at the present. The summit of Mc- 

 Donald is too rough and broken, without soil or vegetation, for shells 

 to live. None were found. 



As these shells show decided differences from any yet collected, 

 they are here given as a separate variety, and description follows. 

 They seem distinct enough to mark a separate species. 



Pyramidula strigosa Gld., var. alpina n. var. 



Shell sni&U ; brownish-gray, tending toward light horn color, in 

 dead shells turning to pearly white ; lustre somewhat silky ; shell flat, 

 little elevated ; lines of growth, under hand lens, fine, an occasional 

 increment of growth giving the appearance of sculpturing; suture 

 well impressed, the periphery well rounded ; aperture nearly circular, 

 slightly obovate, somewhat higher than wide; markings as in strigosa^ 

 the upper band continuing in the spire, gradually disappearing; um- 

 bilicus medium, circular, deep, subcylindric. 



