ring a
strong quacking tendency. This loquacity seems at first a surprising
character to have been acquired under domestication. But the voice
varies in the different breeds; Mr. Brent[450] says that hook-billed
ducks are very loquacious, and that Rouens utter a "dull, loud, and
monotonous cry, easily distinguishable by an experienced ear." As the
loquacity of the Call-duck is highly serviceable, these birds being
used in decoys, this quality may have been increased by selection. For
instance, Colonel Hawker says, if young wild-ducks cannot be got for a
decoy, "by way of make-shift, _select_ tame birds which are the most
clamorous, even if their colour should not be like that of wild
ones."[451] It has been {282} falsely asserted that Call-ducks hatch
their eggs in less time than common ducks.[452]

The Penguin duck is the most remarkable of all the breeds; the thin
neck and body are carried erect; the wings are small; the tail is
upturned; and the thigh-bones and metatarsi are considerably lengthened
in proportion with the same bones in the wild duck. In five specimens
examined by me there were only eighteen tail-feathers instead of twenty
as in the wild duck; but I have also found only eighteen and nineteen
tail-feathers in two Labrador ducks. On the middle toe, in three
specimens, there were twenty-seven or twenty-eight scutellae, whereas in
two wild ducks there were thirty-one and thirty-two. The Penguin when
crossed transmits with much power its peculiar form of body and gait to
its offspring; this was manifest with some hybrids raised in the
Zoological Gardens between one of these birds and the Egyptian
goose[453] (_Anser AEgyptiacus_), and likewise with some mongrels which
I raised between the Penguin and Labrador duck. I am not much surprised
that some writers have maintained that this breed must be descended
from an unknown and distinct species; but from the reasons already
assigned, it seems to me far more probable that it is the descendant,
much modified by domestication under an unnatural climate, of _Anas
boschas_.

[Illustration: Fig. 39.--Skulls, viewed laterally, reduced to
two-thirds of the natural size. A. Wild Duck. B. Hook-billed Duck.]

_Osteological Characters._--The skulls of the several breeds differ
from each other and from the skull of the wild duck in ver