124 THE NAUTILUS. 



56 . Segmentina armigera Say, rather scarce, but found living, 

 under dead leaves, even after prolonged drought. 



57. Physa gyrina Say, rather scarce, a small form, under the 

 same conditions as 56 and 60 ; a larger form is common in a 

 drainage ditch, outside, which is usually dry in summer except 

 after heavy rains. 



58. Aplexa hypnorum Linne, with 61, scarce, small ; one 

 specimen was found with 53. 



59. Amnicola Cincinnati ensis Lea, one dead shell was found in 

 a small ditch (with 52 a), far away from a creek. 



60. Sphserium occidentale amphihium St., common at lower 

 places in the woods ; even after the ground has been dry for 

 weeks, these mussels are found living, at all stages of growth ; 

 not found with 61! 



61. Musadium truncatum Linsley, frequent in pools where 

 water lasts longer, but which are usually dry during summer, 



62. * Pisidium abditum Haldeman, not rare in the ditch 

 mentioned under 57. 



It appears to be worth noting that some species have not 

 been found, which should be expected at such a place rather 

 than many of those listed, e. g. Zonitoides nitidus, Encomdus 

 fidvus, Polygyra multilineata, Bifidaria tappaniana. 



NOTES ON MOLLUSCA OF CENTRAL MONTANA. 



BY S. STILLMAN BERRY, 

 Redlands, California. 



Some two years ago I published in the Nautilus (vol. 26, 

 pp. 130-131) a short list of mollusks taken at Winnecook, 

 Meagher County, Montana, Having had occasion to visit the 

 same locality, and hence the opportunity to make further col- 

 lections, every summer since, it now seems worth while not 

 only to record the additional species which have been found, 

 but to revise the first list in its entirety. A fairly good idea 



