730 



ZOOLOGY 



SECT. XII 



means so prominent as in Sepia. On each side are two apertures, 

 the oral and aboral nepJiridial apertures (a. I, neph. ap.,p. I. neph. ap., 

 p. r. neph. ap.), corresponding to the single pair of Sepia, but not 

 elevated on papillae. Close to each posterior nephridial aperture 

 is an opening the mscero-pericarcUal (l.msc.ap.,r.msc.ap.) lead- 

 ing into the viscero-pericardial section of the body-cavity ; these 

 are not represented in Sepia. In both sexes there are two repro- 

 ductive ducts, right and left ; but in both- the right alone appears 

 to be functional, and the left is much smaller. The opening of 

 the right spermiduct of the male (pen.) is situated on a cylindrical 

 prominence the penis placed close to the middle line. In the 

 female the nidamental glands are, as in Sepia, conspicuous objects, 



jben. 



FIG. 641. Nautilus pompilius, interior of mantle-cavity of a male specimen with the 

 postero-ventral wall reflected, a. 1. neph. ap. oral left nephridial aperture ; an. anus ; cten. 

 ctenidia ; I. cJ ap. left reproductive aperture ; 1. ant. os. left oral osphradium ; I. vise. ap. 

 left viscero-pericardial aperture ; mant. flaps of mantle ; pen. penis ; p. 1. neph. ap. aboral 

 left nephridial aperture ; p. r. neph. ap. aboral right nephridial aperture ; post. os. aboral 

 osphradia ; r. vise. ap. right viscero-pericardial aperture. 



when the mantle-cavity is exposed ; but they are mainly situated 

 on its posterior instead of its anterior wall. 



Enteric Canal. The mouth is surrounded by a peristomial 

 membrane beset with numerous papillae. There is a pair of 

 jaws (Fig. 64i2,jaiv) of similar shape to those of Sepia, but much 

 more powerful, and calcined towards the tips. The buccal mass 

 is a large rounded body with thick muscular walls. On the 

 floor of the contained cavity is a large and prominent odontophore 

 (odont.) with long and pointed curved teeth. In front of the 

 odontophore is a large bilobed soft prominence, the tongue (tong.). 

 Behind the odontophore, between it and the opening of the 

 oesophagus, are one large median and two lateral tongue-like pro- 

 minences beset with papillae ; on the inner surface of the latter 





