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 {h, h) of membrane. In some of the Calamaries, in which 

 the suj^erior salivary glands (i) 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 

 laro-er pair of salivary glands is situated 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 ingluvies, 

 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 

 dispositton 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 Ul 

 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 LoUgo vulgaris, and 

 spirally convoluted in Sepia and 

 Loligo sagittata (f). It receives 

 the biliary secretion between two 

 broad lamella, as in Nautilus. The 

 intestine is very short in all the 

 Dibranchiates. In Octopus it is 

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



