walker: shells of Michigan. 331 



Physa gyrina Say. 



P. ,, var. Hildrethiana Lea. 



P. Sayii Tappan. 



P. vinosa Gld. Gould, Miles, Currier, Smith. 



P. ancillaria Say. 



P. heterostropha Say. 



P. Showalterii Lea. 



P. Warren iana Lea. Currier. 



P. oleacea Tryon. Currier. 



P. deform is Currier. Currier. 



Bulinus hypnorum L. 



B. Tryon i Currier. Currier. "This may prove an extreme 

 form of the above ( B. hypnorum J'' 



Bulinus integer Hald. Currier. 



B. Niagarensis Lea. 



Planorbis lentus Say. Miles. 



P, campanulatus Say. 



P. ,, var, minor. Currier. 



P. multivolvis Case. This remarkable species was dis- 

 covered in the northern part of Michigan. The exact locality is 

 not known and apparently none but the type specimens have ever 

 been found. It is to be hoped that, when the northern part of 

 the state is more thoroughly explored, this long-lost species will 

 be brought to light again. 



Planorbis trivolvis Say. 



P. truncatus Mites, Miles, Currier. 



P. bicarinatus Say. 



P. „ var. corrugatus Currier. 



P. exacutus Say. 



P. deflect us Say. 



P. albus Miill. 



P. parvus Say. 



Segmentina armigera Say. 



