Mallard.

From these several facts, more especially from the drakes of all the breeds
having curled tail-feathers, and from certain sub-varieties in each breed
occasionally resembling in general {281} plumage the wild duck, we may
conclude with confidence that all the breeds are descended from _A.
boschas_.

I will now notice some of the peculiarities characteristic of the
several breeds. The eggs vary in colour; some common ducks laying
pale-greenish and others quite white eggs. The eggs which are first
laid during each season by the black Labrador duck, are tinted black,
as if rubbed with ink. So that with ducks, as with poultry, some degree
of correlation exists between the colour of the plumage and the
egg-shell. A good observer assured me that one year his Labrador ducks
laid almost perfectly white eggs, but that the yolks were this same
season dirty olive-green, instead of as usual of a golden yellow, so
that the black tint appeared to have passed inwards. Another curious
case shows what singular variations sometimes occur and are inherited;
Mr. Hansell[448] relates that he had a common duck which always laid
eggs with the yolk of a dark-brown colour like melted glue; and the
young ducks, hatched from these eggs, laid the same kind of eggs, so
that the breed had to be destroyed.

The hook-billed duck has a most remarkable appearance (see fig. of
skull, woodcut No. 39); and its peculiar beak has been inherited at
least since the year 1676. This structure is evidently analogous with
that described in the Bagadotten carrier pigeon. Mr. Brent[449] says
that, when hook-billed ducks are crossed with common ducks, "many young
ones are produced with the upper mandible shorter than the lower, which
not unfrequently causes the death of the bird." A tuft of feathers on
the head is by no means a rare occurrence; namely, in the true tufted
breed, the hook-billed, the common farmyard duck, and in a duck having
no other peculiarity which was sent to me from the Malayan archipelago.
The tuft is only so far interesting as it affects the skull, which is
thus rendered slightly more globular, and is perforated by numerous
apertures. Call-ducks are remarkable from their extraordinary
loquacity: the drake only hisses like common drakes; nevertheless, when
paired with the common duck, he transmits to his female offsp