678 Dr. HARRIS H. WiLDEft, 



other hand repeated trials of both means of investigation have plainly 

 shown that the branch runs along the inner side of the mandible, 

 close to its surface but without entering the substance of the bone. 



The nerve is sensitive in its function and supplies the inner 

 mucous membrane of the lower lip. 



Vagus (fig. 9, blue [glossopharyngeus also blue]). 



The only difference between Fischer's results and mine with 

 respect to this nerve, lie in the region of the Ramus recurrens. 

 I have given, therefore, several figures demonstrating my conclusions. 

 The main diflerences, it will be noticed, are 1) that the dorso-tra- 

 chealis is supplied by this branch, while 2) the hyo-trachealis is not, 

 but by a separate twig from one of the gill branches. 



The description of the terminal branches of all nerves lying in 

 the nasal region is left to be treated in the section on the nose, q. v. 



VI. The larynx. 



Position. The larynx is situated in the triangular space formed 

 by the parting of the gill arches of the two opposite sides, commencing 

 at the posterior end of basibranchiale 2, and extending nearly as far 

 backwards as the posterior limit of the gill arches, at which point it 

 gradually passes into the trachea. It has the shape of a cylinder or 

 tube, of nearly the same diameter throughout, mainly muscular although 

 containing also cartilaginous and connective tissue elements. 



In the centre of this muscular cylinder lies the lumen of the air- 

 passage, lined with columnar ciliated epithelium, its shape in trans- 

 verse section being cylindrical in the tracheal region , gradually be- 

 coming pyriform , then oval; and finally in the anterior portion of 

 the larynx, it becomes a narrow sUt, extending dorso-ventrally, opening 

 at last into the ventral wall of the oesophagus. 



The space between this lumen and the muscular walls of the tube 

 is filled by dense connective tissue, the same structure being continued 

 anteriorly where the other structures fail, and posteriorly, where it 

 forms the main body of the tracheal walls, containing within its sub- 

 stance the cartilaginous elements. 



Cartilages (fig. 10). The cartilages are four in number, an 

 anterior pair, the arytenoids, and a posterior pair, the cricoids. The 



