The edges of the lower mandible are crossed by numerous fine ridges, which project very little.

Although the beak is thus very inferior as a sifter to that of a shoveller, yet this bird, as every one knows, constantly uses it for this purpose.

There are other species, as I hear from Mr.

Salvin, in which the lamellae are considerably less developed than in the common duck; but I do not know whether they use their beaks for sifting the water.

Turning to another group of the same family.