| | | | | | | | --------------------------------------------------------------------------- On some points in the Anatomy of _Nautilus pompilius_. By T. H. HUXLEY, F.R.S., Professor of Natural History, Government School of Mines. [Read June 3rd, 1858.] Some time ago my friend Dr. Sinclair, of New Zealand, had the kindness to offer me two specimens of the Pearly Nautilus which had been brought to him from New Caledonia, preserved in Goadby's solution. I gladly accepted the present, and looked forward to the dissection of the rare animal with no little pleasure; but on proceeding to examine one of the specimens, I found its anatomical value greatly diminished by the manner in which a deposit from the solution had glued together some of the internal viscera. Other parts of the Nautilus, however, were in a very good state of preservation; and I have noted down such novel and interesting peculiarities as they presented, in the hope that an account of them will be acceptable to the Linnean Society. Of the six apertures which, besides the genital and anal outlets, open into the branchial cavity of _Nautilus pompilius_, one on each side lies immediately above and in front of that fold of the inner wall of the mantle which forms the lower root of the smaller and inner gill, and encloses the branchial vein of that gill. The aperture is elongated and narrow, with rather prominent lips. It measures about 1/8th of an inch. The other two apertures are larger, and lie at a distance of 7/16ths of an inch below and behind the other. They are in close juxta-position, being separated only by a thin triangular fold of membrane, which constitutes the inner lip of the one and the outer lip of the other. The inner aperture is the larger, measuring 3/16ths of an inch in long diameter, and having the form of a triangle with its base directed posteriorly. The outer aperture is not more than 1/8th of an inch long. The two apertures lie just above the edge of the fold of membrane which runs from the inner root of the larger or outer branchia, across the branchial cavity and beneath the rectum, to the other side. These apertures lead into five sacs, which collectively constitute what has been described as the pericardium. The sacs into which the superior apertures open, by a short wide canal with folded walls, are situated on each side of and above the rectum. Their inner boundaries are separated by a space of not less than 5/8ths of an inch in width, in which lie the vena cava and the oviduct. Each cavity has a rounded circumference, and a transverse diameter of about half an inch. In a direction at right angles to this diameter the dimensions vary with its state of distension; but a quarter of an inch would be a fair average.