to much more advantage on the land, "where, by choice, they
spend the greater portion of their time, The stomach of a
spécimen examined by Mr, Thompson contained only minute
seeds and gravel.
Young birds as they appear here in the plumage of their
first winter are greyish-brown. At their second winter, when
they have acquired the white plumage, the irides are orange ;
the head and breast strongly marked with rusty red ; base of
the beak lemon yellow ; whetfulder some continue to exhibit
a tinge of rust colour on the head, after that on the breast
has passed off. The adult bird is of a pure unsullied white $;
the base of the beak' orange yellow ; the irides dark ; the
legs, toes, and membranes black ; the figure at the commencement
of this subject shows the distribution of black
and yellow on the beak, which is liable to a little variation,
The whole length three feet fen inches,,to four feet two
inches? From the carpal joint to the end of . the longest
primary twenty-one inches ; the second and third quill-feathers
longer than the first and fourth ; tail-feathers twenty ;
in young birds I have found but eighteen, and in one instance
nineteen,
M. Temminçk says this species breeds in Iceland in May,
and has been taken in thé winter in Piqardy,
In anatomical structurë this new species differs much more
decidedly from the Hooper than in its external characters.
The principal and most obvious difference is, in the trachea,
which forms One of the best distinctions in the separation of
nearly allied species throughout this numerous family. The
tube of the windpipe is of equal diameter throughout, and
descending in front of the neck enters the keel of the sternum
which is hollow, as in the Hooper, traversing.its whole length,
Having arrived -at the end of the keel, the .tube then gradually
inclining Upwards and outwards passes into a cavity
in the sternum destined to receive it, caused by a separation
of the parallel horizontal plates of bone, forming the posterior
flattened portion of the breast-bone, and producing a convex
protuberance on the inner surface. The tube also changing
its direction from vertical to horizontal, and reaching within
half an inch of the posterior edge, is reflected back after
making a considerable Curve, till it once more reaches the
Jjgel, again traversing which, in a line immediately over the
first portion of the tube, it passes out under the arch of the
merrythought; where, turning upwards, and afterwards backwards,
it enters the body of the bitd to be attached to the
lungs in the usual manner. This is the state of deyelope-
ment in the oldest bird I have yet met with. The degree
next in order, or—younger, differs in having the horizontal
loop of the trachea confined to one side only of the cavity in
the sternum, both sides of which cavity axe at this time formed,
but the loop of the tube is not yet sufficiently elongated
to occupy the whole Space; and the third in order* that on
the right of the three representations shown on the next page,
from a still younger bird, possesses’ only the Vertical insertion
of the fold of the trachea; yet in this specimen the cavity in
the posterior portion of the sternum already exists to a considerable
extent.