INVERTEBRATE PALEONTOLOGY. 597 



being entirely satisfied with its reference to the genus Helix. Until we can 

 have more satisfactory collections for comparison, however, I prefer to leave 

 it provisionally under that name. 



In most, of its characters, this shell seems to resemble a Wyoming form 

 that I have described under the name Vivlparus Wybmingensis, from the 

 Bridger group of the Tertiary series in that region. It evidently has a less 

 elevated spire, however,. and a more decidedly perforated axis. 



The foregoing "cuts represent casts, and consequently the exact nature 

 of the connection of the inner lip with the umbilical region could not satis- 

 factorily he made out. 



Locality and position. — Wind River Valley, Montana ; from the Wind 

 River group. Tertiary ; probably ot the same horizon as the Bridger group 

 in Wyoming. 



