DIGESTION IN CEPHALOPODS. 



23 



7. The apparatus of digestion is very complicated. The 

 mouth is surrounded by a circular lip, and armed with two ver- 

 tical mandibles, which closely resemble the beak of a parrot ; 

 they are set in motion by powerful muscles. A fleshy tongue, 

 furnished with papillae and many horny pieces, occupies the in- 

 terior of this cavity, and is attached to a particular cartilage. 

 Salivary glands, the number and arrangement of which vary a 

 little, surround the pharynx and oesophagus, and pour into the 

 alimentary canal the product of their secretion. The oesopha- 

 gus contracts in general, and before terminating in the stomach, 

 presents a large dilatation or crop (Jig. 10, j) ; but some- 

 times, this first 

 digestive pouch is 

 wanting. Com- 

 monly the stom- 

 ach is in the form 

 of an elongated 

 sack ; its parietes 

 are muscular, and 

 its structure re- 

 minds us of the 

 gizzard of birds. 

 A third cavity (s) ' 

 succeeds this or- as 

 gan, which, in di- 

 branchial cepha- 

 lopods, is in the 1 

 form of a coecum 

 spirally folded, 

 while in the tetra- 

 branchial, it as- 

 sumes that of a 

 spherical sack in- 

 ternally lamella- 



br 



a v 



cb~ 



Flg. 10. VISCERA OF A POULPE. 



Explanation of Fig. 10. Viscera of a poulpe : j. the crop situated be- 

 neath the cephalic cartilage ; gs. inferior salivary glands ; /. mass formed 

 by the liver and ink-bag ; e. excretory duct of the ink-bag going to empty 

 in the funnel ; t. this funnel or tube ; m. the open mantle ; s. the ccecum 

 spirally folded ; i. a part of the intestine, the rest being removed to show 

 the organs situate beneath ; o. the oviducts ; c. the heart ; a. the inferior 

 aorta ; as. the superior aorta ; vb. the branchial veins ; br. the branchiae ; 

 cl. the partition by which these organs adhere to the parietes of the re- 

 spiratory cavity ; ab. the branchial arteries ; cb. venous sinus or branchial 

 hearts ; v. venae cavae ;fm. muscular fasciculi. 



7. What organs constitute the apparatus of digestion in cephalopods ? 

 What is remarkable about the mouth ? What is the character of the 

 stomach ? What is the nature of the liver ? 



