The Descent of Man

demia), in the red beak of the chough (Corvus
graculus, Linn.), of the black swan, and the
black stork. This leads me to remark that it is
not incredible that toucans may owe the enormous
size of their beaks to sexual selection, for
the sake of displaying the diversified and vivid
stripes of colour, with which these organs are
ornamented. (51. No satisfactory explanation
has ever been offered of the immense size, and
still less of the bright colours, of the toucan's
beak. Mr. Bates ('The Naturalist on the Amazons,'
vol. ii. 1863, p. 341) states that they use
their beaks for reaching fruit at the extreme tips
of the branches; and likewise, as stated by other
authors, for extracting eggs and young birds
from the nests of other birds. But, as Mr. Bates
admits, the beak "can scarcely be considered a
very perfectly-formed instrument for the end to
which it is applied." The great bulk of the beak,
as shewn by its breadth, depth, as well as
length, is not intelligible on the view, that it
serves merely as an organ of prehension. Mr.