dly
in another sense be called a monstrosity. A series may be formed
commencing with the black-boned Silk fowl, which has a very small crest
with the skull beneath penetrated only by a few minute orifices, but
with no other change in its structure; and from this first stage we may
proceed to fowls with a moderately large crest, which rests, according
to Bechstein, on a fleshy mass, but without any {266} protuberance in
the skull. I may add that I have seen a similar fleshy or fibrous mass
beneath the tuft of feathers on the head of the Tufted duck; and in
this case there was no actual protuberance in the skull, but it had
become a little more globular. Lastly, when we come to fowls with a
largely developed crest, the skull becomes largely protuberant and is
perforated by a multitude of irregular open spaces. The close relation
between the crest and the size of the bony protuberance is shown in
another way; for Mr. Tegetmeier informs me that if chickens lately
hatched be selected with a large bony protuberance, when adult they
will have a large crest. There can be no doubt that in former times the
breeder of Polish fowls attended solely to the crest, and not to the
skull; nevertheless, by increasing the crest, in which he has
wonderfully succeeded, he has unintentionally made the skull
protuberant to an astonishing degree; and through correlation of
growth, he has at the same time affected the form and relative
connexion of the premaxillary and nasal bones, the shape of the orifice
of the nose, the breadth of the frontal bones, the shape of the
post-lateral processes of the frontal and squamosal bones, the
direction of the axis of the bony cavity of the ear, and lastly the
internal configuration of the whole skull together with the shape of
the brain.

_Vertebrae._--In _G. bankiva_ there are fourteen cervical, seven dorsal
with ribs, apparently fifteen lumbar and sacral, and six caudal
vertebrae;[431] but the lumbar and sacral are so much anchylosed that I
am not sure of their number, and this makes the comparison of the total
number of vertebrae in the several breeds difficult. I have spoken of
six caudal vertebrae, because the basal one is almost completely
anchylosed with the pelvis; but if we consider the number as seven, the
caudal vertebrae agree in all the skeletons. The cervic