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Rh, natural selection (as distinct from sexual) seems excluded, unless it could be shown that the change of colour is correlated with some still greater advantage, and this is neither apparent nor likely. There remains sexual selection, which to my mind is strongly suggested. The modified colouring is, it is true, shared by the two sexes, but this is quite compatible with the theory, which supposes the tintings of the male kingfisher and numerous other brilliant birds to have been thus acquired and transmitted in each stage of progress to the female. It would, therefore, be interesting, though, no doubt, difficult, to determine by observation whether the creamy-coloured male birds were on an average more attractive to the females than the other kind, and also whether the more handsome form was increasing. In regard to the last point, this was the opinion of a man guiltless of theories, but with a large amount of experience of the birds.

Of these two species of skua, the great and the lesser or Arctic one, the latter appears to me to be the boldest and most aggressive. It will chase not only gulls, but ocasionally the great skua also, this last, as it would seem, for sport or pleasure rather than for any particular object. In the same way they often chase each other. A too near approach to the nest may, perhaps, be the reason in either case, but having watched them attentively I do not think that the pursuing bird is often under any real apprehension. Gulls are persecuted by them in the manner I have described, and sometimes, I think, also in mere wantonness. The larger ones seem never to resist, but the kittiwake will sometimes go down upon the water,