OF THE MOLLUSC A OF IOWA. 79 



Unio ellipsis Lea. Common in eastern Iowa, Mississippi 

 river at Keokuk, Fort Madison, Burlington, Muscatine ; 

 Iowa river at Iowa City. 



Uniofragosus Conrad. Des Moines river, rare ; Raccoon 

 river, common ; some of the largest and finest specimens 

 from Iowa are from the latter stream. Also abundant in 

 the Iowa river at Iowa City. 



Unio gibbosus Barnes. Des Moines, Skunk, Shell Rock, 

 Iowa, Cedar and Mississippi rivers : common. U. archior 

 is only a variety having a white nacre. 



Unio gracilis Barnes. Eastern Iowa : common. 



Unio graniferus Lea. Rare. Collected in the Missis- 

 sippi river at Muscatine, May 29, 1886. 



Unio higginsi Lea. The type of this species was col- 

 lected near Muscatine and described in the Journal of the 

 Academy of Natural Sciences of Philadelphia, 2nd series, 

 volume V. It is certainly very closely allied to, if not 

 identical with, U. orbiculatus Hald. 



Unio irroratus Lea. Eastern Iowa : rare. 



Unio lachrymosus Lea. Not uncommon at Des Moines, 

 Iowa City, and Burlington. Very abundant in the Des 

 Moines river at Bonaparte, Van Buren county. It is often 

 received under the name of U. asperrimus which is a syn- 

 onym. 



Unio IcBvissimus Lea. Common at Iowa City and else- 

 where in the eastern part of the state. This is one of the 

 few alate species occurring in this region. 



Unio ligamentinus Lamarck. One of the most abundant 

 species occurring everywhere throughout the state. Its 

 most northern locality known is the Rum river above 

 Anoka, Minnesota, and from there it is said to range 

 to western New York, northern Alabama and southern 

 Kansas. This is one of the Uniones, that is sometimes 

 gregarious ; hundreds often being found together in a 



