The nest of the ruby-throat is of a most delicate nature; the external parts being formed of a little grey lichen found on the branches of the trees, glued together by the saliva of the bird, and neatly arranged round the whole of the nest, as well as to some distance from the spot where it is attached to the branch or stem itself. The interior is lined with a cottony substance; and the innermost, with the silky fibres obtained from various plants. Within this little nest the female humming-bird lays two white and nearly oval eggs; generally raising two broods in the season. In one week, says Audubon, the young are ready to fly, but are fed by the parents for nearly another week. They receive their food direct from the bill of their parents, who disgorge it in the manner of canaries and pigeons. It is my belief that no sooner are the young able to provide for themselves than they associate with other broods, and perform their migrations apart from the old birds, as I have observed twenty or thirty young humming-birds resort to a group of trumpet-flowers, when not a single old bird was to be seen. The plumage of the female is in most respects like that of the male, except that she is not possessed of the brilliant feathers on the throat which especially distinguish him. Although there are several other species of humming-birds which live permanently in the Southern States of the Union, or migrate northward in summer, we cannot now inspect them. We shall have, however, many opportunities of examining a number of the species when we come to visit South America. Although the number of birds and the variety of their species inhabiting North America is very great, except those we have mentioned, they do not in general possess any very interesting peculiarity, which might tempt us to linger longer amongst them, and we will therefore wander on and inspect some of the curious reptiles which inhabit various parts of the American States and Canada. THE COW-BIRD.