312 AVERS. [Vol. VI. 



pass on to the surface of the head, where they again supply 

 canal organs of the lateral line system. The VII enters the 

 auditory chamber and gives off nerves to ear sense organs in 

 forms as high as the saurian Reptilia, and it is possible in the 

 Mammalia as well, though the latter point has not been proven. 

 The IX nerve enters the auditory chamber and gives off a nerve 

 to the sensory apparatus of the ear in Elasmobranch fishes at 

 least. 



There has been great difference of opinion as to whether the 

 facial nerve really gave off a branch to the ear in Petromyzon, 

 and the whole matter has been summed up by Julin (1890), who 

 says (p. 819), after showing that all the anatomists who have 

 studied the facial in Petromyzon are agreed that this nerve 

 makes its way into the auditory capsule to traverse it and pass 

 out again from its anterior lower corner: "Pendant son trajet 

 a travers la capsule auditive, le nerf facial fournirait, d'apres 

 Schlemm et d' Alton au vestibule membraneux un petit rameau 

 nerveux, qu'ils appellent ne?'/ aiiditif accessoire. Cet fait a 

 ensuite ete confirme par Ketel. Ce rameau du facial a ete 

 egalement mentionne par J. Miiller comme existant chez les 

 Myxinoids. Furbringer sans en nier I'existence, n'a pu cepen- 

 dant le decouvrir, ni chez Myxine ghitinosa, ni chez les Petromy- 

 zons. Wiedersheim, qui n'a pu non plus en deceler la presence 

 chez Petromyzon, emet I'idee que ce nerf acoustique accessoire 

 de Schlemm et d' Alton ne serait autre chose que le nerf oculo- 

 moteur externe (abducens). Enfin, Ahlborn n'a par non plus 

 signale cette branche du nerf facial. Pas plus que ces auteurs, 

 je n'ai pu en trouver la moindre trace chez I'Ammocoetes." 

 This branch is present in the ear, and it is more probable that 

 those authors who have studied this nerve specially and who 

 have followed it through its whole course have described it cor- 

 rectly than that those who have failed to find the nerve have 

 really proven the absence of such a facial branch. We know 

 from Ahlborn's studies that the recurrent branch sends facial 

 fibres into both the glossopharyngeal and the lateral nerves. 



According to His, Sr., the auditory nerve is purely a gan- 

 glionic nerve, and the same is true of the taste fibres of the IX. 

 As is well known, the sensory fibres subserving the sense of 

 taste in the anterior two-thirds of the tongue run through the 

 chorda tympani, and the recent investigations of Sapolini make 



