672 



Mil. J. GftAttAM KEBE ON THE 



[June 18, 



In the sexually mature animal the much coiled-up spermatophore 

 mass occupies the cavity of the 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 C(;rner the cavity of JS'eedham's sac passes 

 into the penis. This is a somewhat cylindroidal, flattened structure 

 about 10 mm. in length and 8 mm. 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 



"■«.-' 



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 



coelom. 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 repi-eaents the 



line along which the mantle-flap is reflected headwardg. 



