gantic palate, and serve to
strain or sift the water, and thus to secure the minute prey on which
these great animals subsist. The middle and longest lamina in the
Greenland whale is ten, twelve, or even fifteen feet in length; but in
the different species of Cetaceans there are gradations in length; the
middle lamina being in one species, according to Scoresby, four feet,
in another three, in another eighteen inches, and in the Balaenoptera
rostrata only about nine inches in length. The quality of the whalebone
also differs in the different species.

With respect to the baleen, Mr. Mivart remarks that if it "had once
attained such a size and development as to be at all useful, then
its preservation and augmentation within serviceable limits would be
promoted by natural selection alone. But how to obtain the beginning of
such useful development?" In answer, it may be asked, why should not
the early progenitors of the whales with baleen have possessed a mouth
constructed something like the lamellated beak of a duck? Ducks,
like whales, subsist by sifting the mud and water; and the family has
sometimes been called Criblatores, or sifters. I hope that I may not
be misconstrued into saying that the progenitors of whales did actually
possess mouths lamellated like the beak of a duck. I wish only to show
that this is not incredible, and that the immense plates of baleen in
the Greenland whale might have been developed from such lamellae by
finely graduated steps, each of service to its possessor.

The beak of a shoveller-duck (Spatula clypeata) is a more beautiful
and complex structure than the mouth of a whale. The upper mandible is
furnished on each side (in the specimen examined by me) with a row or
comb formed of 188 thin, elastic lamellae, obliquely bevelled so as to
be pointed, and placed transversely to the longer axis of the mouth.
They arise from the palate, and are attached by flexible membrane to
the sides of the mandible. Those standing towards the middle are the
longest, being about one-third of an inch in length, and they project
fourteen one-hundredths of an inch beneath the edge. At their bases
there is a short subsidiary row of obliquely transverse lamellae. In
these several respects they resemble the plates of baleen in the mouth
of a whale. But towards the extremity of the beak they differ much, as
they project inward, instead of straight downward. The entire head of
the shoveller, though incomparably less