Ungulinidae
Ungulinidae is a family of marine bivalve molluscs in the order Venerida. Characteristics. The members of this family are found in muddy sand or gravel at or below low tide mark. They have characteristically rounded shells with forward-facing umbones (projections). The valves are flattened and deeply etched with concentric rings. Each valve bears two cardinal and two plate-like lateral teeth. These molluscs do not have siphons but the extremely long foot makes a channel which is then lined with slime and serves for the intake and expulsion of water.