82 AN ANNOTATED CATALOGUE 



Unio spaiulatus Lea. Rare in many of the streams of 

 eastern Iowa, common in the Raccoon river in Dallas 

 county. 



Unio subroslratus Say. Iowa City, Muscatine and else- 

 where in eastern Iowa. Known to Iowa collectors under 

 Conrad's name U. mississippiensis. Prof. R. E. Call's 

 careful studies of this group have led him to the following 

 conclusions relative to the synonymy of this species. 



1831. Unio subroslratus Say. 



1834. Unio nashvillensis Lea. 



1850. Unio mississippiensis Conrad. 



1852. Unio nigerrinus Lea. 



1859. Unio rulervillensis Lea. 



1868. Unio topekoensis Lea. 



Uiio tenuissimus Lea. Rare, but not uncommon in the 

 Iowa river at Iowa City. 



Unio trigonus Lea. Des Moines, Iowa, Cedar, Missis- 

 sippi and other streams : common. 



Unio triangularis Barnes. Eastern Iowa : rare. 



Uniotuberculatus^nYWQS. Generally distributed through- 

 out the state, but nowhere abundant. 



Unio undulatus Barnes. Abundant in central and west- 

 ern Iowa ; represented by U. plicatus in the eastern part 

 of the state. 



Unio ventricosus Barnes. Rock river, northwestern 

 Iowa : common in central and western Iowa ; the variety oc- 

 cidens being more common in the eastern part of the state. 



Unio verrucosus BiU'ues. Eastern Iowa : not common. 



Unio wardii Lea. Des Moines river : common ; eastern 

 part of the state : rare. In the Raccoon river in Dallas 

 county, this species occurs in greater abundance than in 

 any other locality known ; it is very closely related to U. 

 metanever Raf. but is more compressed, and typical speci- 

 mens have a delicate rose-tinted nacre. 



