58 Naturai. History Bulletin. 



Genus Goniobasts, — Lea. 

 G. CUBICOIDES. — Auth. 



Reported from the Cedar river by Prof. F. M. Witter. 



F AM I L Y— R I SSO I DiE . 



•S UB- FAMIL T—HTDROBIINy^. 

 Genus BithyneUa. — Moquin- Tandon. 

 B. OBTUSA.- — Lea. 



Locally common on muddy bottoms in quiet waters. Read- 

 ily distinguished from Auinicola by its more elongated form 

 and obtuse spire. 



Genus Pyrgnlopsis. — Call and Pilshry. 

 P. MississiPPiENsis. — Call and Pils. 



This interesting little Rissoid was discovered near the mouth 

 of the Rock river in Illinois. 



While not strictly an lozua moUusk it occurs so' near that it 

 is extremely probable that it occurs on the Iowa side of the 

 Mississippi river. Its habitat is on muddy bottoms. 



Genus Amnicola.— Gould and Hald. 



A. CINCINNATENSIS. Allth. 



Very common on muddy bottoms in ponds and sluggish 

 streams. 



A. LIMOSA. — Say. 



Very common on muddy bottoms of ponds and on lily leaves 

 and sticks, particularly in June during oviposition. 



6- UB-FAMIL 1 '—LITHOdL TPHIN^^. 

 Genus Somatogyrus. — Gill. 

 S. suBGLOBOsus. — Say. 



Quite common on muddy bottoms in quiet streams. This 

 is the form which is commonly called S. isoo-onus. Say. 

 S. INTEGER. — Say. 



Locally very common on rocks in rapid streams. Very 



