IOWA CITY LOESS. 201 



*POLYGYRA HIRSUTA (Say) Pils. 



Locally quite widely distributed in deeper woods, though 

 never gregarious. Fossil shells are found sparingly in the 

 western loess at Council Bluffs, la. 



*POLYGYRA MONODON {Rack.) Pils. 



This species is very similar to the preceding in its 

 habits, and in the distribution of both the recent and fossil 

 forms, both, however, being rather more abundant. 

 Neither has been found fossil at Iowa City, though their 

 discovery would not be surprising. Common in the loess 

 at Natchez, Miss ., and also fossil in Indiana. 



*STROBILOPS VIRGO (Pils.). 



Locally common on rocky, shaded slopes. It is occa- 

 sionally found fossil in the western loess. This has 

 ordinarily been reported as Strobila labyrinthica Say. 



Vertigo milium (Gld.) Binn. 



Not common, on mossy banks and slopes. Not found 

 fossil. Its minute size might easily cause it to be over- 

 looked. 



** Vertigo ovata Say. 



Rare, on mossy, shaded banks, sometimes on lower 

 grounds. Somewhat more common as a fossil, occurring 

 sparingly in several of the exposures. 



* Vertigo bollesiana (Morse.) 



Rare, on mossy banks, usually in shady places. It is 

 rare in the western loess. 



*Vertigo tridentata Wolf. 



Locally common, usually on rather exposed rocky, moss- 

 covered banks. Found sparingly in the western loess. 



**C0CHLIC0PA LUBRICA (Mull.). 



Rare on rather open slopes, etc. It is more common as 



