rghs_ I have examined four skulls (male and female) of the
pencilled sub-breed, and one (male) of the spangled sub-breed; the
nasal bones stand remarkably wide apart, but in a variable degree;
consequently narrow membrane-covered spaces fare left between the tips
of the two ascending branches of the premaxillary {262} bones, which
are rather short, and between these branches and the nasal bones. The
surface of the frontal bone, on which the branches of the premaxillary
rest, is very little depressed. These peculiarities no doubt stand in
close relation with the broad flattened rose-comb characteristic of the
Hamburgh breed.

[Illustration: Fig. 34.--Skulls of natural size, viewed from above, a
little obliquely. A. Wild _Gallus bankiva_. B. White-crested Polish
Cock.]

I have examined fourteen skulls of _Polish and other crested breeds_.
Their differences are extraordinary. First for nine skulls of different
sub-breeds of English Polish fowls. The hemispherical protuberance of
the frontal bones[428] may be seen in the accompanying drawings, in
which (B) the skull of a white-crested Polish fowl is shown obliquely
from above, with the skull (A) of _G. bankiva_ in the same position. In
fig. 35 longitudinal sections are given of the skulls of a Polish fowl,
and, for comparison, of a Cochin of the same size. The protuberance in
all Polish fowls occupies the same position, but differs much in size.
In one of my nine specimens it was extremely slight. The degree to
which the protuberance is ossified varies greatly, larger or smaller
portions of bone being replaced by membrane. In one specimen there was
only a single open pore; generally, there are many variously-shaped
open spaces, the bone forming an irregular reticulation. A medial,
longitudinal, arched ribbon of bone is generally retained, but in one
specimen there was no bone whatever over the whole protuberance, and
the skull when cleaned and viewed from above presented the appearance
of an open basin. The change in the whole internal form of the skull is
surprisingly great. The brain is modified in a corresponding manner, as
is shown in the two longitudinal sections, {263} which deserve
attentive consideration. The upper and anterior cavity of the three
into which the skull may be divided, is the one which is so greatly
modified; it i