The Capulidae, the cap snails or cap shells, are a taxonomic family of limpet-like sea snails, marine gastropod molluscs in the clade Littorinimorpha. Capulidae is the only family in the superfamily Capuloidea. According to taxonomy of the Gastropoda by Bouchet & Rocroi (2005) the family Capulidae has no subfamilies. The name Trichotropidae was previously used for this family, but this name is invalid, as it is a junior synonym.