THE NAUTILI'S. 41 



Orcokcli.r cooperi maxima Pils. 



Oreohelix pygnuea Pils. 



Oreohelix strigosa Gld. (depressa Ckll. V) 



Oreohelix strigosa extremitatis Pils. & Ferr. 



Physa sayi Tappati 



Planorbis bicarinatus (antrosus Conr. ) 



PomatiopsAs robusta Walker 



PupUla muftcorum (L.) 



Pyramidulii cronkhitei anthonyi Pils. 



Pyramidula striated Aiith. 



Succinea avara Say 



Vallonia cyclophorella Aucey 



Vitrina pfeifferi Newc. (alaskana Ball) 



Oreohelix cooperi minor should be eliminated from the list, 

 because, in the first place, a re-examination of the material so 

 recorded shows that it is true cooperi, and in the second place, 

 investigations recently carried on by me at the type locality 

 of minor convince me that the small form so named was 

 based upon examples merely dwarfed by adverse conditions 

 in one portion of a normal cooperi colony. Baker has placed 

 the Ft. Bridger record of Lymn<ra elodes var. in the synonymy 

 of L. palustris. The Pyramidula striatella record is probably 

 P. c. anthonyi, which would still further reduce the list, but 

 it may possibly be P. shimeki cockerelli Pils. Pupilla mus- 

 corum is probably P. m. xerobia Pils., but one cannot be cer- 

 tain of it. Physa sayi is doubtful, but if not that, it refers to 

 some other Physa, so its elimination would not reduce the 

 number of species. This leaves a list of about 22 species, 12 

 of which are confined to two genera, with no recorded pele- 

 cypods at all. Possibly some recorded species have been over- 

 looked by me. The only large land snails are in the genus 

 Oreohelix; Polygyra, which occurs to the northward in Mon- 

 tana, not having been found in Wyoming. Oreohelix is an 

 ancient genus in the state, 0. grangeri Ckll. & Hend. and 0. 

 megarche Ckll. & Hend. occurring in rocks of Eocene age. 



Our two weeks' work, besides furnishing new localities for 

 some of the species already recorded from the state, adds the 

 following species, including four additional genera, two of 

 which are pelecypods: 



