OCR Text |
Show 672 MR. J. GRAHAM KERR ON THE [June 18, In the sexually mature animal the much coiled-up spermatophore mass occupies the cavity of tbe sac bending round the edge of the septum. The internal surface of the sac-wall is smooth to the naked eye, while a low-power lens discloses the existence of minute glandular-looking rugae running on the whole parallel to the axis of the spermatophore mass. At its anterior inner corner the cavity of Needham's sac passes into the penis. This is a somewhat cylindroidal, flattened structure about 10 m m . in length and 8 m m . greatest breadth, attached to the body-wall within the mantle-cavity. Its walls are thick and muscular, and its cavity is divided by a sagittal longitudinal septum, which does not extend quite to the tip of the organ, into Fig. 3. Penis Diagram of the testis, genital duct, and penis of the male Nautilus. The rudimentary genital duct of the left side is dotted in. T, testis : at its upper end is seen its aperture into the general cavity of the ccelom. Ac.Gl, accessory gland with internal opening of the vas deferens beneath the crescentic flap at its left-hand corner. Sp.Sac, spermatophore sac. The curved line traversing the diagram from side to side represents the line along which the mantle-flap is reflected headwards. |