1917.] NATURAL SCIENCES OF PHILADELPHIA. 55 



the northern end and examined the western shore at various places. 

 We found no living moUusks in the lake itself. This may be due to 

 the fact that the water was considerably above the usual level and we 

 were not prepared for dredging. The sloughs and streams of the 

 valley furnished quite a number of species of fresh-water mollusks 

 alive, and the mountains and canyons bordering the valley yielded 

 land snails. 



Sta. 67, just within the mouth of Montpelier Canyon, northwest 

 of Montpelier, Idaho, on the south side of the canyon. Oreohelix 

 cooperi (W. G. B.) abundant, mostly immature, under shrubbery on 

 slope beneath a limestone ledge almost devoid of rock slides. Al- 

 though the snow from a two days' storm (June 20-21) was just 

 melting, on June 22 the snails were all active and hence easy to find. 

 Mature examples from this station measure about 20 mm. in diameter. 

 Vitrina alaskana Dall was noted on a ditch bank. This Vitrina we 

 found at almost every station where we found Oreohelix, but we did 

 not always collect it and perhaps in some instances failed to record 

 it in the notebook. 



Sta. 68, three miles up Montpelier Canyon, on the north side of a 

 ravine that comes in from the east. Oreohelix cooperi (W. G. B.) 

 plentiful, nearly all mature, in limestone rock slides, mature examples 

 varying from 17 mm. to 21.5 mm. in diameter, mostly about 20 mm. 



Sta. 69, south side of the same gulch, opposite Sta. 68 and not 

 more than 150 feet distant. Oreohelix cooperi (W. G. B.), live 

 examples scarce, dead shells plentiful, under shrubbery on a limestone 

 slope devoid of rock slides. Though separated from Sta. 69 only by 

 the narrow bed of the gulch and with the more favorable north 

 exposure, the snails here are much smaller, the shells varying from 

 13.5 mm. to 15.5 mm. in diameter. Lack of cover does not appear 

 to be the cause of the difference in size, as the cover at Sta. 67 is 

 about the same. 



Sta. 70, canyon about two miles north of Montpelier. Oreohelix 

 cooperi (W. G. B.), of fair size, but not plentiful, in edges of limestone 

 slides. 



Sta. 71, a short distance up Bennington Canyon, east of Benning- 

 ton (north of Montpelier). Oreohelix cooperi (W. G. B.), large, 

 robust, very abundant under shrubbery, especially wild roses, on 

 steep banks of creek, active among the tiny patches of snow remaining 

 from the late storm. None found in the big sandstone slides on the 

 slope above the brush and trees of the narrow bottomland. 



Sta. 72, sloughs on east side of Bear River, on both sides of the 

 Montpelier-Ovid wagon road. We here obtained the following: 



