326 LECTURE XXIH. 



ened by a muscular bulb (<j^ to the extent of nearly half an inch. 

 An elongated pyriform sac (o) is attached by a contracted origin 

 near the root of a large aorta, and dilates to a width of two lines ; 

 then, again contracting, becomes connected by its other extremity 

 to the venous sinus : it contained a firm coagulated substance. 

 M. Valenciennes does not appear to have noticed this peculiar 

 organ. The anterior aorta supplies the nidamental gland, and ad- 

 joining part of the mantle, and the rectum ; then bends back to form 

 the small artery (jw), continued along the membranous siphon (5). 

 The large aorta supplies the gizzard and ovary, winds round the 

 bottom of the abdominal sac, sends off large branches to the liver, and 

 regains the dorsal aspect of the crop along which it passes to the 

 oesophagus, distributing branches on either side to the great shell- 

 muscles. It bifurcates near the beginning of the oesophagus, and 

 terminates by furnishing branches to the mouth, the surrounding 

 parts of the head and funnel. 



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

 oviduct, and, as in the Pectinibranchiate Gasteropods, of an ac- 

 cessory glandular nidamental apparatus. The ovary (Jig. 129. m) 

 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 com- 

 pressed 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 different sizes, 

 which are attached by one extremity to the ovarian capsule, but are 

 free and ])erforated at the opposite end ; are smooth exteriorly, but 

 rugose and apparently granular on the inner surface, owing to nu- 

 merous minute wavy plicae adhering thereto. The largest of the 

 ovisacs were four or five lines in length ; they were principally at- 

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

 vessels penetrated the ovary. 



The oviduct {Jig- 129.*') 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 

 is probable, however, that the ova derive an additional exterior co- 

 vering and connecting substance from the seci'etion of a large glan- 

 dular apparatus, which is situated immediately below the terminal 

 orifice of the oviduct. This apparatus is attached to the mantle, and 



