noted the spasmodic manner in which the tail was from time to time suddenly bent down. It is true that it then tightly clasped—as one may almost call it—the edge of the nest, pressing hard against it on the outer side. But though such action may now have become part of a shaping process, yet it was impossible for me, when I saw it, not to think of the Peewit, in which something markedly similar could have answered no purpose of this kind. Were the latter bird instead of rolling on the ground to do so in a properly constructed nest of a size suitable to its own bulk, the tail, upon being bent forcibly down in the way I have mentioned, would compress the rim of it just as does that of the Blackbird. And were the Blackbird to go through the motions which I witnessed, on the bare ground and side by side with the Peewit, a curious parallel would, I think, be exhibited. To these two I may add the Rook, and—from recent observation—the Australian or Black Swan. Similarity of the cup of many built nests to the cup-shaped hollow in which so many ground-laying birds deposit their eggs, is, indeed, a significant thing, and the significance is increased when we see the same or very similar movements employed in the shaping of both.
In the case of these Peewits it is true that the pairing, when I saw it, did not take place on the same spot where the rolling afterwards did. Nevertheless, the distance was not great, and it varied considerably. The run which preceded the rolling commenced immediately on the consummation of the nuptial rite, and if this run, which varied in length, were to become shorter and ultimately to be eliminated altogether, the bird would then be pairing, rolling, and, at last, as seems to me highly probable, laying its eggs in one and the same place. That these strange activities should succeed, and not precede, the actual pairing is indeed a curious thing; but I suggest that the rolling of a single bird differs only, in its essential character, from actual pairing, by the fact of its being single, and that, thus, the primary sexual instinct contains, and gives birth to, the secondary nest-making one. At any rate, in the Peewit, movements of a highly curious nature immediately succeed, and seem, thus, to be related to, the act of pairing, and whilst these movements, as a whole, bear a peculiar stamp (expressed by the term "sexual "), some of them, not separable from the tout ensemble, suggest, also, the making of a
