2 4 o COMPARATIVE ANATOMY 



maxillae superioris * ) and to the anterior wall of the 

 spiracle. 



The main branch of the seventh nerve is continued out- 

 wards as the hyoidean or post-spiracular nerve. Running 

 beneath the post orbital process of the auditory capsule it 

 passes below the attachment of the post-spiracular ligament f 

 to the wall of the auditory capsule, and lies between the 

 posterior edge of the ligament and the hyomandibular 

 cartilage. Emerging just behind the spiracle the nerve 

 divides into three branches, the anterior of which is dis- 

 tributed to the skin and mucous canals on the side of the 

 head, the middle branch runs in the depression between 

 the ceratohyal and mandibular cartilages and supplies the 

 mucous membrane of the buccal cavity, while the posterior 

 branch supplies the anterior part of the constrictor superficialis 

 branchiarum muscle. It should be noted that the seventh 

 nerve forks over the spiracle just as the fifth nerve forks over 

 the mouth opening. 



The eighth nerve is the auditory ; it passes straight into 

 the auditory capsule and divides into two main branches, 

 the anterior supplying the utriculus and the ampullae of the 

 anterior and external horizontal canals, the posterior supplying 

 the sacculus and the ampulla of the posterior semicircular 

 canal. 



The ninth nerve originates from the ventro-lateral border 

 of the medulla opposite the middle of the auditory capsule, 

 and entering the latter runs through a canal which traverses 

 it diagonally. Emerging near the posterior angle of the 



* According to Vetter, this muscle is innervated by a twig from the 

 fifth in Acanthias. In Scyllium it is supplied by two slender nerves, one 

 of which is certainly a branch of the seventh. The other possibly runs 

 back in the connective tissue sheath of the seventh, and joins the fifth, but 

 I haye not yet satisfied myself on this point. G. C. B. 



t The ligament which originates from the wall of the auditory capsule, 

 and is inserted partly on the outer end of the hyomandibular cartilage, 

 partly on the palato-quadrate cartilage is post-spiracular, as shown in fig. 

 57, L. I cannot find any trace in Scyllium of the pre-spiracular ligament 

 so commonly figured and described. There is a stout connective tissue 

 band passing from the post-orbital process to a thick sheet of sub-dermal 

 connective tissue overlying the adductor mandibuli muscle. But it is 

 not attached either to the palato-quadrate or the hyomandibular cartilage, 

 and is hollow, being pierced by a canal connected with the mucous canal 

 system. G. C. B. (See also Ridewood, Anatomischer Anzeiger, 1896. 



