y little
except in the proportional length and curvature of the premaxillaries.
These latter bones in the Call-duck are short, and a line drawn from
their extremities to the summit of the skull is nearly straight,
instead of being concave as in the {283} common duck; so that the skull
resembles that of a small goose. In the hook-billed duck (fig. 39)
these same bones as well as the lower jaw curve downwards in a most
remarkable manner, as represented. In the Labrador duck the
premaxillaries are rather broader than in the wild duck; and in two
skulls of this breed the vertical ridges on each side of the
supra-occipital bone are very prominent. In the Penguin the
premaxillaries are relatively shorter than in the wild duck; and the
inferior points of the paramastoids more prominent. In a Dutch tufted
duck, the skull under the enormous tuft was slightly more globular and
was perforated by two large apertures; in this skull the lachrymal
bones were produced much further backwards, so as to have a different
shape and to nearly touch the post. lat. processes of the frontal
bones, thus almost completing the bony orbit of the eye. As the
quadrate and pterygoid bones are of such complex shape and stand in
relation with so many other bones, I carefully compared them in all the
principal breeds; but excepting in size they presented no difference.

[Illustration: Fig. 40.--Cervical Vertebrae, of natural size. A. Eighth
cervical vertebra of Wild Duck, viewed on haemal surface. B. Eighth
cervical vertebra of Call Duck, viewed as above. C. Twelfth cervical
vertebra of Wild Duck, viewed laterally. D. Twelfth cervical vertebra
of Aylesbury Duck, viewed laterally.]

_Vertebrae and Ribs._--In one skeleton of the Labrador duck there were
the usual fifteen cervical vertebrae and the usual nine dorsal vertebrae
bearing ribs; in the other skeleton there were fifteen cervical and ten
dorsal vertebrae with ribs; nor, as far as could be judged, was this
owing merely to a rib having been developed on the first lumbar
vertebra; for in both skeletons the lumbar vertebrae agreed perfectly in
number, shape, and size with those of the wild duck. In two skeletons
of the Call-duck there were fifteen cervical and nine dorsal vertebrae;
in a third skeleton small ribs were attached to the so-called fifteenth
cervical ve