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Rh have to use its wings some time before it had reached its least possible velocity. Bearing this in mind, it was shown that a diminution in velocity of 11.6 feet a second could be compensated for by an increase of one degree in the angle at which the bird happened to be flying; and that, therefore, it was extremely probable that the albatros used its air cells to enable it to slightly shift its centre of gravity with respect to the position of its wings, and so, with little muscular exertion, to alter the angle at which it was flying. The essayist concluded his able and instructive paper by stating that he did not pretend to have solved the problem connected with the flight of the albatros, but merely to have suggested a method of solving it. Experiments required to be made respecting the resistance offered by the front and under surface of the bird to different velocities of wind before any satisfactory conclusion could be arrived at.

A vote of thanks was tendered to Captain Hutton for the care and ability he had shown in the preparation of this paper.

2. "Notes on Land and Fresh-water Shells collected in the Northern Part of the Province of Auckland, during the Month of April, 1868," by T. B. Gillies.

After a few introductory remarks, the author observed that, at the native settlement of [Waitatiora] Whitiora, he had found a fine specimen of the Bulimus crawling across the path, which appeared to be the Bulimus antipodarum, but differing from some hundreds of specimens that he had seen, in having two strongly developed bars or projections on the inner side of the outer lip. The presence of half-burnt shells, on peat, at Whangaruru, from which the fern had been previously burnt off, afforded ample evidence that it had once been a favourite habitat of the Bulimus antipodarum. A smaller shell, which he was inclined to set down as the young of the Bulimus antipodarum, or an Achatina, had been obtained from the natives. None of the larger Bulimus antipodarum had been found at Bream Head, though abundance of the smaller kind were met with. However, he had some doubt of the identity of the Whangaruru with the Bream Head species. On Mania Hill, near Whangarei, he had found what at first sight appeared to be three varieties of a whorled shell, like a Turritella, but which he supposed to be a Cyclostoma. The larger variety had six whorls, about half an inch long by one-eighth of an inch in width, and of a brownish colour, indistinctly striped; the mouth being nearly circular and much contorted to the right, with a sort of double lip all round. The smaller variety, five whorls, a quarter of an inch to three-eighths of an inch long, had not the contorted mouth nor the double lip. The smaller variety was only ten-twelfths of an inch in length, by .7 in. wide. He had also obtained a large number of