though still adult birds, as a pair which I caught in Sark when only flappers, and brought home in July, 1866, had few or no brown streaks about their heads in the winter of 1877-8, and in the winter of 1878-9 their heads are almost as white as in the breeding-season.  These birds had their first brood in 1873, and have bred regularly every year since that time, and certainly have considerably more white on their primary quills than when they first assumed adult plumage and began to breed.  Probably this increase of white on the primaries as age increases, even after the full-breeding-plumage is assumed, is always the case in the Herring Gull, and also in both the Lesser and Greater Black-backs, thus distinguishing very old birds from those which, though adult, have only recently assumed the breeding-plumage.  I know Mr. Howard Saunders is of this opinion, certainly as far as Herring Gulls are concerned.  Besides the live ones, two skins I have, both of adult birds, as far as breeding-plumage only is concerned, are evidently considerably older than the other.  No. 1, the youngest of these,—­shot in Guernsey in August, when just assuming winter plumage, the head being much streaked, even then, with brown, showing that though adult it was not a very old bird,—­has the usual white tip on the first primary, below which the whole feather is black on both webs, and below that a white spot on both webs, for an inch; the white, however, much encroached upon on the outer part of the outer web by a margin of black.  In No. 2, probably the older bird, the first primary has the white tip and the white spot running into each other, thus making the tip of the feather for nearly two inches white, with only a slight patch of black on the outer web.  On the second primary of No. 1 the white tip is present, but no white spot; but on the same feather of No. 2 there is a white spot on the inner web, about an inch from the white tip; this would, probably, in a still older bird, become confluent with the white tip, as in the first primary.  I have not, however, a sufficiently old bird to follow out this for certain.  In No. 1, the older bird, the pale grey on the lower part of the feathers also extends farther towards the tip, thus encroaching on the black of the primaries from below as well as from above.  I think these examples are sufficient to show that the white does encroach on the black of the primaries as the bird grows older, till at last, in very old birds, there would not be much more than a bar of black between the white tip and the rest of the feather; and this is very much the case with the tame ones I caught in Sark in 1866, and which are therefore, now in the winter of 1879, twelve and a half years old; but I do not believe that at any age the black wholly disappears from the primaries, leaving them white as in the Iceland and Glaucous Gulls.  The Herring Gull is an extremely voracious bird, eating nearly everything that comes in its way, and rejecting