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 papillse 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 {fg. 10, j) ; but some- 

 e gs j gs 



/■ 



br 



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- ^^ 

 gan, which, in di- 

 branchial cepha- 

 lopods, is in the 

 form of a coecum 

 spirally folded, 

 while in the tetra- 

 branchial, it as- 

 sumes that of a 

 spherical sack in- 

 ternally lamella- 



Fig. 10. — VISCERA OF A TOULPE. 



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

 neatli 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 ; — 7n. the open mantle ; — s. the coecum 

 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 ; — hr. the branchise ; 

 — 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. vense cavoe ',—ftn. muscular fasciculi. 



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

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

 Btomach ? What is the nature of the liver ? 



