A whale's mouth is furnished with very numerous horny plates, which hang down from the palate along each side of the mouth.

They thus form two longitudinal series, each plate of which is placed transversely to the long axis of the body, and all are very close together.

On depressing the lower lip the free outer edges of these plates come into view.

Their inner edges are furnished with numerous coarse hair-like processes, consisting of some of the constituent fibres of the horny plates--which, as it were, fray out--and the mouth is thus lined, except below, by a network of countless fibres formed by the inner edges of the two series of plates.
This network acts as a sort of sieve.

When the whale feeds it takes {41} into its mouth a great gulp of water, which it drives out again through the intervals of the horny plates of baleen, the fluid thus traversing the sieve of horny fibres, which retains the minute creatures on which these marine monsters subsist.