128 



AVERS. 



[Vol. VI. 



cuius durch die ganze Schnecke sich erstrecken und die eigent- 

 liche membrana tectoria uberlagern, aber durchaus nicht an sie 

 angeheftet so dass wir auch hier eine doppelte Absonderung 

 der Zellen des Schneckenrohres annehmen miissen." 



TABLE OF MEASUREMENTS OF SOME OF THE STRUCTURES 



COMPOSING THE MAMMALIAN COCHLEA. 



{Measurements given in mm.~) 



THE TESTIMONY OF THE NERVE SUPPLY. 



The vertebrate ear is then composed of canal organs and 

 their canals ; and since it existed at one time in its phyloge- 

 netic, as well as in its ontogenetic history in a superficial posi- 

 tion, its nerves, like the other cranial nerves which supply the 

 canal sense organs at the present day, must have been either 

 (i) an entire cranial nerve or (2) branches of one or more such 

 nerves. It can be shown, I think, that the ear is supplied by 

 two distinct nerves which have widely different origins in the 

 brain, and are in reality brandies from tivo nerves, and so not a 

 discrete cranial nerve, as has formerly been supposed to be the 

 case. In our anatomies the auditory nerve is recognized, fol- 

 lowing the classification of Sommering, as a distinct cranial 

 nerve, the eighth in number of a series of twelve. However, 



