Note:  Do not rely on this information. It is very old.

Natatores

Natatores (Swimmers), in some classifications, an order of birds, containing those which are partially or entirely web-footed. There are four groups or families: (1) Auks, Penguins, Guillemots, Divers, Grebes; (2) Gulls, Terns, and Petrels; (3) Pelicans, Cormorants, Gannets, Frigate-birds, Tropic-birds, and Darters; (4) Ducks, Geese, and Flamingoes.