THE NAUTILUS. 135 



3500 Pisidium spp. (loose valves). 

 373 Vallonia gracilicosta Reinh. 



2 Carychium exiguum Say. 

 23 Pupoides marginatus (Say). 

 20 Bifidaria armifera Say. 

 5 Bifidaria contracta Say. 

 5 Bifidaria pellucida hordeacella Pils. 

 136 Bifidaria procera cristata Pils. & Van. 

 2 Pupilla muscorum (L. ). 

 5 Vertigo sp. 



5 Cochlicopa lubrica (Miill. ). 

 2 Polita indentata (Say). 



400 Zonitoides minuscidus (Binn.). 



13 Helicodiscus eigenmanni arizonensis Pils. & Fer. 

 2 Succinea sp. 



15 Planorbis antrosus Conrad. 

 100 Planorbis parvus Say. 

 100 Physa virgata Gld. 



6 Ancylus rivularis Say. 



4500 Paludeslrina seemani (Ffld.). 



There were also 75 seeds of " Snow-on- the-Mountain," Di- 

 chrophyllum marginatum (Pursh), but they may have been 

 blown into the weathered material recently and hence may not 

 be fossil. They are entirely unaltered. 



The same collectors obtained 30 Planorbis antrosiis Conrad and 

 5 Physa sp. about two miles below the head of the North Spring 

 River west of Roswell, but did not bring in any of the weath- 

 ered material or stop to examine the deposit thoroughly. 



NOTES ON ACELLA HALDEMANI (DESH.) BINNEY. 



BY FRANK C. BAKER. 



Notes on the ecology of this the slenderest of our Lymnaeas 

 are rare, and its whereabouts during a large part of the year 

 has been a matter of conjecture. Dr. Reynold J. Kirkland of 

 Grand Rapids, Michigan, has collected the species extensively 

 and his observations are of interest in connection with the 



