PLANORBIS. 197 



Subgenus A D U L A, H. Adams. 



11. PLANORBIS MULTIVOLVIS, Case. 

 Plate 6, fig. 1, 2. 



Whorls seven, about half the last whorl 

 overlapping the preceding one, sometimes the 

 last whorl suddenly distorted and expanded 

 for the last half of its length ; right side con- 

 cave, left side slightly acuminate and cari- 

 nate ; throat campanulate ; aperture opening 

 towards the left, but projecting on both sides 

 beyond the preceding whorl. 



Diameter 15 mill. 



Northern Michigan. 



(44) 



