622 



LECTURE XXIV. 



recurved spines, which must assist in the further comminution and 

 deglutition of the food. The fauces are also provided with spinige- 

 rous folds (/*, A) of membrane. In some of the Calamaries, in which 

 the superior salivary glands (^) penetrate the folds, the ducts open 

 upon the inner surface, as in the Nautilus. In the Octopus the an- 

 terior or upper salivary glands are on the outside of the buccal mass. 

 In most of the Dibranchiates, including the Spirula, a second and 

 larger pair of salivary glands is s^ituated on each side of the oeso- 

 phagus, at the commencement of the abdominal or hepatic cavity ; 

 their ducts unite to terminate below the tongue in the concavity of 

 the lower mandible. 



The peritoneal membrane is divided and disposed as in the Nau- 

 tilus, in order to form special receptacles for the different viscera. 

 The oesophagus, in all the Dibranchiates, is narrower than in the 

 Nautilus ; its inner surface is disposed in longitudinal plicae : in both 

 the Octopus and Argonaut it dilates, 226 



soon after having passed through 

 the cranium, into a long ingluviesj 

 forming a large cul-de-sac at its 

 commencement; but in the Deca- 

 pods {fig. 226, a) it continues nar- 

 row and of uniform breadth to the 

 stomach. This cavity (c) is an 

 elongated sac, presenting, in the 

 disposition of its muscular fibres, in 

 the proximity of the cardiac {d) and 

 pyloric (e) orifices, and in the thick- 

 ness of the epithelial lining, the usual 

 characters of the gizzard. The in- 

 testine, at a short distance from y, 

 the pylorus {e), communicates with 

 a glandular and laminated sac {g), 

 analogous to that in Nautilus, and 

 presenting a similar globular form 

 in Rossia and Loligopsis ; it is 

 elongated in Loligo vulgaris, and 

 spirally convoluted in Sepia and 

 Loligo sagittata {f). It receives 

 the biliary secretion between two 

 broad lamella3, as in Nautilus. The 

 intestine is very short in -all the 

 Dibranchiates. In Octopus it is 

 bent upon itself {fig. 227. r), as in 



Loligo sagittata. 



