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DUCKS. 89 LAMELLIROSTRAL SWIMMERS. (ORDER ANSERES.) Ducks, Geese, and Swans. (Family Anatid^.) This family contains some two hundred species, and is represented in all parts of the world. It includes five subfamilies: the Mergansers {Mergince), or Fish-eating Ducks; the Pond or River Ducks {Anatincv), the Bay or Sea Ducks {FuliguliricB); the Geese {Anserinck); and the Swans {Cygnince). Ducks, like all hunted birds, are exceedingly wild, and comparatively few species will come within reach of the student's opera-glass. The group may therefore be reviewed briefly. The Mergansers or Shelldrakes, num- bering three species, have narrow, serrate bills which enable them to hold the fish they pursue and catch under water (see Fig. 18). The Eiver Ducks have little or no lobe or flap on the hind toe. In this group belong our Mallard, AYidgeon, Pintail, Blue-winged and Green-winged ^'pkte v^' Teals, Black Duck, Wood Duck, and others. All but the last two nest in the North and are found in our latitude only during their spring and fall migrations, or, if the weather be mild, in the winter. The Black Duck and Wood Duck nest rarely in the Middle States. All these birds feed in shallow water by " dabbling " or " tipping," tenns which will be readily understood by any one who has watched domesticated Ducks feeding. The Bay and Sea Ducks, on the contrary, are divers, and may descend to the bottom in water more than one hundred and fifty feet in depth. They are to be dis- tinguished from the River Ducks by the presence of a flap or lobe on the hind toe. The commoner members of 14