Round-rib elimia
The round-rib elimia, scientific name Elimia nassula, is a species of freshwater snail with an operculum, an aquatic gastropod mollusks in the family Pleuroceridae. This species is endemic to the United States. References 

Molluscs of the United States
Elimia
Gastropods described in 1834
Taxa named by Timothy Abbott Conrad
Taxonomy articles created by Polbot