The Mollusc a of Eastern Iowa. * 6^ 



state. It also occurs in the western portion, but in what abun- 

 dance we are unable to say. 

 L. HUMiLis. — Say. 



Locally very common on mud near ponds and streams. 

 Quite variable. 



Geims Physa. — Drap. 

 P. LORDL — Baird. 



A form occasionally occurs which has been referred to this 

 species by Prof. R. E. Call. It may be simply a large form 

 of P. heterostrofha with deeply-folded columella. 



P. HETEROSTROPHA. Say. 



Locally very common in ponds and sluggish streams. Of- 

 ten mistaken for the following species but quite distinct. 



P. GYRiNA. — Say. 



The most common of our Physas. It is found in every 

 pond and sluggish stream. It is a narrower shell with more 

 elevated spire, less convex whorls, less inflated body-whorl 

 and smaller aperture than the preceding. 

 P. sAYi. — (?) Ta-pfan. 



A species which we can not place anywhere else, was found 

 by us at Cedar Rapids and less commonly at Iowa City. It 

 has been referred by some of our correspondents to P. hete- 

 rostropka but it is certainly distinct. As compared with P. 

 heterosfropha it is more ventricose taken as a whole, though 

 with proportionally less inflated body-whorl, has a less im- 

 pressed suture and the sheU is much Hghter in texture. There 

 may be some question as to its being P. sayi, but it certainly 

 is distinct from all other forms here listed. 

 P. ANCiLLARiA. — (?) Say. 



Specimens probably belonging to this species are not un- 

 common. 



P. VIRGATA. G/d. 



Found by Prof. Witter at Muscatine. 



