GANNET, SECOND YEAR.
The white plumage of the neck is just beginning to appear.
Gannets present one or two structural peculiarities of sufficient interest to mention here. In most birds, it will be remembered, the nostrils open on each side of the beak; but in the gannet no trace of true nostrils remains; and the same may almost be said of the cormorant and darter. In gannets, however, a slight indication of their sometime existence remains, though the nostril itself no longer serves as an air-passage; and these birds are compelled to breathe through the mouth. Again, the tongue, like the nostrils, has also been reduced to a mere vestige. Stranger still is the fact that immediately under the skin there lies an extensive system of air-cells of large size, which can be inflated or emptied at will. Many of these cells dip down between the muscles of the body, so that the whole organism is pervaded with air-cells, all of which are in connection with the lungs.
Photo by Scholastic Photo. Co.] [Parson's Green.
GANNET, FULL PLUMAGE.
The fully adult plumage is not attained till the bird is three years old.
The Frigate- and Tropic-birds, which now remain to be described, are probably much less familiar to our readers than the foregoing species.
Photo by Valentine & Sons, Ltd.] [Dundee.