THE NAUTILUS. 131 



state of Montana, so that the following list of species from the upper 

 Musselshell Valley, in the central part of the slat**, is of interest 

 from a distributional standpoint. The exact locality is Winnecock, 

 Meagher County, where the writer has done a little collecting dur- 

 ing August of two succeeding years (191 1-1912). The fresh-water 

 species were taken in the various springs and overflow pools border- 

 ing the Musselshell River, and the terrestrial species occurred under 

 sticks, leaves and stones in the more moist places among the sur- 

 rounding coltonwoods. No species were taken in the swift-flowing 

 waters of the river itself, and no land forms were found at a greater 

 distance from the river than a few rods. All except Vertigo bin- 

 neyana, Zonitoides tnimiscufa and Planorbis callioglyptus were of 

 fairly frequent occurrence. The elevation of Winnecock is about 

 4000 feel about sea level. 



Vallonia costata montana Sterki. The specimens appear to cor- 

 respond very well with Dr. Stciki's diagnosis, and specimens sent to 

 Mr. George H. Clapp were similarly determined by him. They are 

 possibly the same as the " Vallonia gracillcosta var. t close to cottata 

 Say," of Squyer's list. 



Vitrea radiatula Alder (hammonis Strom.). 



Zonitoides arborea (Say). 



Zonitoides minuscula (Binney). 



Euconulus fulvtis (Miiller). 



Agriolimax campestris (Binney) var. The specimens are perhaps 

 to be referred to the montanus of Ingersoll. 



Pyrnmidula cron&hitei (Newcomb) near var. anthonyi Pilsbry. 



Succinea avara Say. 



S/icciiiea retusa Lea. 



Lyrnnaa paluttris Miiller. 



Lymntea caper ata Say. 



Planorbis parvus Say. 



Planorbis callioglyptus Vanatta. A single poor specimen is thus 

 somewhat doubtfully determined. 



Planorbis nntrosus Conrad (= bicarinatus Say). 



Pliysa ayrina Say var. 



Aplexa hypnomm Linn 6. 



