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Rh mature tint being, in all of them, so vivid and so often exposed—unless sexual selection has been the operating cause? We would not, I suppose, find a corresponding difference in the colour of the internal organs, according to the age of the bird.

The mother guillemot, now, for the first time whilst I have been here, utters that guttural, yet sharp "ik, ik, ik," note, which, two years ago, in June and early July, was the only one I ever heard on the ledge I watched so closely. When another fish is brought in there is some more of it, mixed with the jodel-ing; so that it seems now to be becoming more frequent. But never have I been able to make out with anything like clearness that the chick has uttered any note at all. No undoubted sound from it has reached me. The time before last that it was fed, however, I thought I heard a sharp little cry, but it was impossible to be sure whether this was from the chick or some of the thronging and clamouring kittiwakes perched and flying all about. In any case, it was nothing particular.

On the ledge, where there were fifteen birds yesterday, there are now only eight; on my ledge, which from here I see in its entirety, only the mother and chick, another bird—not the father—having just flown off. On all the others together I make out only thirty-six. I see but one other chick, but a bird is sitting as if she might have one under her. Nothing can be plainer than that the old birds have stayed behind on the ledges after the young ones