The red-breasted merganser (Merganser serrator) inhabits both hemispheres. It is called also sawbill, harle, and sheldrake. The American merganser (M. Americanus) and the hooded merganser (Lophodytes cucullatus) are well-known species. White merganser, the smew or white nun.
Origin: Sp. Mergansar, fr. Mergo a diver (L. Mergus, fr. Mergere to dip, dive) _ ansar goose, L. Anser.