CEPHALOPODA. 323 



processes over the mandibles and their retractor muscles to the labial 

 process of the opposite side. 



The tongue is supported by a horny, slightly curved, and transversely 

 striated plate. The fleshy substance of the tongue forms three dis- 

 tinct papillose caruncles anteriorly, into which the retractor muscles 

 are inserted. The dorsum of the tongue is incased by a thin layer 

 of horny matter, supporting four longitudinal rows of recurved spines; 

 behind which the surface is again soft and papillose. Two broad 

 duplicatures of mucous membrane project forwards from the sides of 

 the pharynx; they each include a simple layer of salivary follicles, the 

 secretion of which escapes by a single perforation in the middle of 

 the process. 



The lining membrane of the pharynx is disposed in numerous 

 longitudinal folds, w^here it begins to contract into the oeso- 

 phagus. This tube, having passed through the nervous collar, dilates 

 into a capacious crop, from the bottom of which a contracted canal, 

 half an inch in length, is continued to an oval gizzard. The intestine 

 commences near the cardiac orifice, and soon communicates with a 

 small round laminated pouch, through which the biliary secretion 

 passes to the intestine. This tube forms two abrupt inflections, and 

 terminates in the branchial cavity near the base of the funnel close to 

 the proboscidian end of the oviduct. 



The epithelium of the oesophagus and ingluvies is developed into a 

 thick cuticular membrane, with minute ridges in the gizzard. In the 

 specimen dissected by me the crop and gizzard were laden with the frag- 

 ments of a small crab, the pieces being more comminuted in the gizzard. 



The liver is a bulky gland, extending on each side of the crop as 

 low down as the gizzard ; it is divided into four lobes, connected 

 posteriorly by a fifth transverse portion : the lobes are subdivided into 

 numerous lobules of an angular form. The secretion of the bile is 

 derived, as in other mollusks, from arterial blood ; it is conveyed 

 from the liver by two main trunks, which unite into one duct, about 

 two lines from the laminated sac. The bile, having entered the 

 sac, is diverted by a peculiar development and disposition of one 

 of the laminae from flowing towards the gizzard. The follicular 

 structure of this and the other folds of membrane indicate their 

 glandular character; and the entire laminated pouch may be con- 

 sidered as a more developed form of pancreas than the simple 

 caecum which represents that gland in some of the Gasteropods. 

 No other foreign secretion enters the alimentary canal, as there is 

 not any ink-gland in the Pearly Nautilus. 



The heart and large vessels, with their follicular appendages, are 

 contained in a large cavity, subdivided into several compartments, 



Y 2 



