palate; and it seems to be quite within the scope of natural selection to preserve all favourable variations, until the points were converted, first into lamellated knobs or teeth, like those on the beak of a goose — then into short lamellae, like those of the domestic ducks — and then into lamellae, as perfect as those of the shoveller-duck — and finally into the gigantic plates of baleen, as in the mouth of the Greenland whale.

In the family of the ducks, the lamellae are first used as teeth, then partly as teeth and partly as a sifting apparatus, and at last almost exclusively for this latter purpose.

With such structures as the above lamellae of horn or whalebone, habit or use can have done little or nothing, as far as we can judge, towards their development.