The RUBY-THROATED FAIRY HUMMING BIRD (_Trochilus colubris_) is easily recognisable by its awl-shaped beak, of medium size, and compressed at its base, its short, slender foot, long, narrow wing, and slightly-forked tail. The mantle and centre tail-feathers are green, enlivened with gold; the sides of the neck, throat, and breast are of a brilliant ruby-red, spotted with black; the rest of the under side is greyish white, intermixed with green; the quills and tail-feathers are purplish brown; the eye dark brown, and the beak and foot black. In the male the entire under side is white, and the three exterior tail-feathers relieved by a white spot. The length of the body is three inches and a half, and the breadth four inches and a quarter. This species is found in all the eastern portions of the United States. [Illustration: THE BRAZILIAN FAIRY (_Heliothrix auriculata_).] This beautiful little bird is pre-eminently migratory in its habits, a great portion of its life being spent in passing from north to south, and _vice versâ_. "The Ruby-throated Humming Bird," says Wilson, "makes its first appearance in Georgia, from the south, about the 23rd of March. As it passes on to the northward, as far as the interior of Canada, where it is seen in great numbers, the wonder is excited how so feebly-constructed and delicate a little creature can make its way over such extensive regions of lakes and forests among so many enemies, all its superiors in strength and size; but its very minuteness, the rapidity of its flight, which almost eludes the eye, and its admirable instinct or reason are its guides and protectors. About the 25th of April it usually arrives in Pennsylvania, and about the 11th of May begins to build its nest. This is generally fixed on the upper side of some horizontal branch, not among the twigs, but where it is attached by the side to an old moss-grown trunk; others may be found fastened on a strong, rank stalk or weed in the gardens, but these cases are rare. The nest, which is usually placed on a branch some ten feet from the ground, is about one inch in diameter, and as much in depth, and the outer coat of one now lying before me is formed of a small species of blueish grey lichen, thickly glued on with the saliva of the bird, giving firmness and consistency to the whole, as well as keeping out moisture. Within this are thickly-matted layers of the fine wings of certain flying seeds, closely laid together, and lastly the downy substance from the great mullein and from the stalks of the common fern lining the whole. The two eggs are pure white, and of equal thickness at both ends. On a person approaching their nest, the little proprietors dart around with a humming sound, passing within a few inches of his head, and should the young be nearly hatched the female will resume her place on the nest, even while the spectator stands within a yard or two of the spot. The precise period of incubation I am unable to give, but the young