JAWS OF ONYCHOTEUTHIS. 575 



the mouth are seized and dragged backwards, by a kind of peristaltic 

 motion, to the commencement of the ossophagus (I). The necessity of 

 the provision thus made for enabling the Cephalopods to swallow the 



Fig. 288. 



Section of the oral apparatus of Onychoteuthis : a, circular lip surrounding the mouth ; 

 6, d, horny beak ; c, cartilaginous substance forming the bulk of the mandible ; e, i, muscular 

 tongue ; f, g, A, lobes upon its surface; k, salivary glands ; I, oesophagus. 



substances upon which they feed must be at once apparent ; for, seeing 

 that the walls of the mouth are formed entirely by the hard and in- 

 flexible horny beak, it is difficult to conceive how deglutition could have 

 been accomplished by any other contrivance. 



(1540.) Four salivary glands pour a copious supply of saliva into the 

 oral chamber : of these, two, situated on the sides of the root of the 

 tongue, give off distinct ducts, which terminate near the commence- 

 ment of the oesophagus ; while the other pair, generally larger than 

 the superior, are lodged in the visceral sac on each side of the upper part 

 of the crop. The inferior salivary glands each furnish an excretory 

 canal ; but their two ducts soon unite into a single tube which, with 

 the oesophagus, passes through the ring formed by the cranial cartilage, 

 and, piercing the fleshy mass of the mouth, opens in the neighbourhood 

 of the spiny portion of the tongue, so that the secretion furnished at 

 this point serves to moisten the aliment as it is taken up by the 

 lingual hooks to be swallowed. In Onychoteuihis two salivary glands 

 (fig. 288, 7c) are situated at the root of the tongue ; and their ducts are 

 pointed out in the drawing by pins introduced into their orifices. 



