The Mollusca of Eastern Iowa. 75 



U. EBENUs. — Lea. 



Common in the Mississippi river. Rare at Iowa City. 

 U. ELEGANS. — Lea. 



Common in the larger streams, particularly among stones 

 on muddy bottoms. Sometimes pink-nacred and varying in 

 coloration as much as U. doiiacifonnis. 

 U. ELLIPSIS. — Lea. 



Common in all the larger streams. Young shells are rayed. 

 U. FRAGOSUS. — Con. 



This interesting species was very common a few years ago 

 in the Iowa river at Iowa City, but it is becoming rare. Over 

 a bushel of tine specimens was taken by us in 1883. Young 

 shells are beautifuU}'- marked with green. The epidermis is 

 remarkable for its silky appearance. This species is remark- 

 ably constant in its characters. 

 U. GiBBOSUS. — Barnes. 



Very common in the Mississippi, Skunk and Shell Rock 

 rivers. White-n acred forms are called U. arctior. A rayed 

 specimen in the University Cabinet, which is marked U. 

 arctior., is a young U. rectus. 



U. GRACILIS. — Barnes. 



Very common in the larger streams on both muddy and 

 sandy bottoms. Usually rayed. Old specimens lose the- wing. 

 U. GRANiFERUs. — Lea. 



Regarded as distinct from U verrucosus by Prof. R. E. Call, 

 and by him reported from Iowa. 

 U. LACHRYMOSus. — Lea. 



Found in the Skunk, Iowa and Mississippi rivers. Also in 

 the northwestern and western parts of the state. 

 U. L^vissiMUs. — Lea. 



Quite common on muddy bottoms in the larger streams. 

 The epidermis is highly polished. Old specimens are scarcely 

 alate. 



