The genera and species are numerous. They are divided into river ducks and sea ducks. Among the former are the common domestic duck (anas boschas); the wood duck (Aix sponsa); the beautiful mandarin duck of china (Dendronessa galeriliculata); the muscovy duck, originally of south America (Cairina moschata). Among the sea ducks are the eider, canvasback, scoter, etc.
Bombay duck, a small aquatic mammal of australia, having webbed feet and a bill resembling that of a duck (ornithorhynchus anatinus). It belongs the subclass monotremata and is remarkable for laying eggs like a bird or reptile; called also duckbill, platypus, mallangong, mullingong, tambreet, and water mole.