Lastly, in this our rapid survey of the distribution of the feathered tribes, we have to speak of those whose element is the air. And here, perhaps, the reader may feel inclined to remark that, with the exception of the cursorial birds, such as the Ostriches and the Apteryx, all the species we have had occasion to mention are more or less capable of flight--that this is the special attribute of the whole class. Nevertheless, upon a little consideration, he will find that amongst the many races that fly well, there are some so pre-eminent in this respect that all others quail before them. It is one thing to be able to fly, and another to be furnished with wings so powerful that they never seem to tire. It is one thing to be the champion of the coppice, but another to be the tyrant of the sky! The greatest powers of flight are of course conferred upon the rapacious birds, whose business is to overtake and destroy their swift-flying prey. To enable them to do this, their wings are necessarily of the most perfect structure; and they may also be recognised by their feet, which are strong, and armed with formidable talons. Of the swiftness of the falcon we have spoken elsewhere; and any one who has witnessed the flight of the eagle is not likely to have forgotten so grand a spectacle; his movements are majestic, and as he sails above the clouds on outstretched wings he seems to feel himself the monarch of the scene around. And yet even the falcon and the eagle cannot, as regards their powers of flight, be looked upon as the most highly gifted of flying birds. The spread of wing of the frigate-birds measures ten feet from tip to tip, and their flight is so powerful that they are everywhere to be seen in tropical climates at immense distances from land; while the albatross has been known to fly around a ship for weeks together, exhibiting such indomitable strength of wing that it has been supposed to be capable of circling round the world. It is by no means our intention to trouble the reader with unnecessary details concerning the anatomy of the creatures upon the history of which he is about to enter; nevertheless, it is indispensably requisite that we should give at least an outline of their internal organisation.