What is "acroloxidae"

Acroloxidae, commonly known as river limpets, are a taxonomic family of very small, freshwater snails, aquatic pulmonate gastropod limpet-like mollusks with a simple flattened conical shell in the clade Hygrophila.

Acroloxidae is the only family within the superfamily Acroloxoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).