of both species which I have kept, and noted their various changes from time to time, and from skins of both:  unfortunately the two skins of the youngest birds I have are not quite of the same age, one being that of a young Herring Gull, killed at the Needles in August,—­the other a young Lesser Black-back, killed in Guernsey in December; but I do not think that this difference of time from August to December, the birds being of the same year, makes much difference in the colour of the feathers; at least this is my experience of live birds:  it is not till the next moult that more material distinctions begin to appear; after that there can be no doubt as to the species.  Two young Herring Gulls which I have, and which I saw in the flesh at Couch’s shop just after they had been shot, seem to me worthy of some notice as showing the gradual change of plumage in the Herring Gull; they were shot on the same day, and appear to me to be one exactly a year older than the other; they were killed in November, when both had clean moulted, and show examples of the second and third moult.  No. 1, the oldest, has the back nearly uniform grey, and the rump and upper tail-coverts white, as in the adult.  In No. 2, the younger one, the grey feathers on the back were much mixed with the brownish feathers of the young bird, and there are no absolutely white feathers on the rump and tail-coverts, all of them being more or less marked with brown.  The tail in No. 2 has the brown on it collected in large and nearly confluent blotches, whilst that of No. 1 is merely freckled with brown.  But perhaps the greatest difference is in the primary quills; the first four primaries, however, are much alike, those of No. 1, being a little darker and more distinctly coloured; in both they are nearly of a uniform colour, only being slightly mottled on the inner web towards the base; there is no white tip to either.  In No. 1 the fifth primary has a distinct white tip; the sixth also has a decided white tip, and is much whiter towards the base, the difference being quite as perceptible on the outer as on the inner web.  The seventh has a small spot of brown towards the tip on the outer web, the rest of the feather being almost uniform pale grey, with a slightly darker shade on the outer web, and white at the tip; the eighth grey, with a broad white tip.  In No. 2 the fifth primary has no white tip; the sixth also has no white tip, and not so much white towards the base; the seventh is all brown, slightly mottled towards the base, and only a very slight indication of a white tip; and the eighth is mottled throughout.  I think it worth while to mention these two birds, as I have their exact dates, and the difference of a year between them agrees exactly with young birds which I have taken in their first feathers and brought up tame.  I may also add, with regard to change of plumage owing to age, that very old birds do not appear to get their heads so much streaked with brown in the winter as younger