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Darwin, Charles, 1809-1882

"The Origin of Species by means of Natural Selection, 6th Edition"

The
trumpeter and laugher, as their names express, utter a very different coo
from the other breeds. The fantail has thirty or even forty tail-feathers,
instead of twelve or fourteen, the normal number in all the members of the
great pigeon family: these feathers are kept expanded and are carried so
erect that in good birds the head and tail touch: the oil-gland is quite
aborted. Several other less distinct breeds might be specified.
In the skeletons of the several breeds, the development of the bones of the
face, in length and breadth and curvature, differs enormously. The shape,
as well as the breadth and length of the ramus of the lower jaw, varies in
a highly remarkable manner. The caudal and sacral vertebrae vary in
number; as does the number of the ribs, together with their relative
breadth and the presence of processes. The size and shape of the apertures
in the sternum are highly variable; so is the degree of divergence and
relative size of the two arms of the furcula. The proportional width of
the gape of mouth, the proportional length of the eyelids, of the orifice
of the nostrils, of the tongue (not always in strict correlation with the
length of beak), the size of the crop and of the upper part of the
oesophagus; the development and abortion of the oil-gland; the number of
the primary wing and caudal feathers; the relative length of the wing and
tail to each other and to the body; the relative length of the leg and
foot; the number of scutellae on the toes, the development of skin between
the toes, are all points of structure which are variable.


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