590 LECTURE XXIII. 



passes to the oesophagus, distributing branches on either side to the 

 great shell-muscles. It bifurcates near the beginning of the ceso- 

 phagus, and terminates by furnishing branches to the mouth, the 

 surrounding parts of the head and funnel. 



In the male Nautilus, at the part of the branchial cavity where 

 the vulva opens in the female, there is a short conic penis, somewhat 

 bent at the basis towards the ventral side, having an obtuse and per- 

 forated apex ; a very narrow canal extends from this aperture to the 

 base, and there expands into a pouch, of a firm parchment-like 

 texture. This pouch contained a conglobate tube of a brown colour, 

 of little more than a line in diameter : the walls of the tube consisted 

 of an external transparent membrane, and an internal thicker tunic 

 of circular fibres. In the interior of the tube was a narrow band 

 disposed in close spiral convolutions. Between the spiral band and 

 tube were several free oblong or navicular microscopic corpuscles. 

 For so much knowledge of the male organs of the Nautilus — all that 

 science hitherto possesses — we are indebted to Van der Hoeven.* 



The female organs of the Nautilus consist of an ovary, an oviduct, 

 and, as in the Pectinibranchiate Gastropods, of an accessory gland- 

 ular nidamental apparatus. The ovary {fig, 214, ii) is situated at. 

 the bottom of the sac on the right side of the gizzard in a peritoneal 

 cavity peculiar to itself. It is an oblong compressed body, one inch 

 and a half in length, and an inch in breadth ; convex towards the 

 lateral aspect, and on the opposite side having two surfaces sloping 

 away from a middle longitudinal elevation. At the anterior and 

 dorsal angle there is an orifice about three lines in diameter, with a 

 puckered margin, which conducts into the interior of the ovary. It 

 is filled with numerous oval ovisacs of diff'erent sizes, which are 

 attached by one extremity to the ovarian capsule, but are free and 

 perforated at the opposite end ; are smooth exteriorly, but rugose 

 and apparently granular on the inner surface, owing to numerous 

 minute wavy plicae adhering thereto. The largest of the ovisacs 

 were four or five lines in length ; they were principally attached 

 along the line of the exterior ridge, at which part the nutrient vessels 

 penetrated the ovary. 



The oviduct (^fig. 2 1 4, i;) is a flattened tube of about an inch in length, 

 and from four to five lines in breadth ; it extends forward by the side 

 of the intestine, and terminates at the base of the funnel close to the 

 anus. It becomes enlarged towards the extremity, and is deeply 

 furrowed in the transverse direction both within and without ; the 

 parietes are also here thick and pulpy, and apparently glandular. It 



* CCCXC. 



