230 



COMPARATIVE ANATOMY 



respect, as well as in the more highly-specialised histological struc- 

 ture of the cochlea, lies the characteristic peculiarity of the auditory 

 organ of Mammals. The auditory nerve forms the axis of the spiral. 

 In consequence of this development of the cochlea, the papilla 



Fig. 184. — Right Membkan'Ous Labyrinth of Rabbit (Lepu-i cunicnhix.) 

 A, from the inner, and B from the outer side. (After G. Retzius.) 



sus, sinus utricularis sacculi ; esc, canalis reimiens Henseni ; rh, basilar brancli of 

 tlie auditory nerve (ac) ; /, facial nerve ; mb, basilar membrane ; //.■•■, spiral 

 ligament. (Other letters as Figs. 180-183.) 



acustica, oi-, as it is called in Mammals, the organ of Corti, is drawn 

 out to a considerable length, and the part of the wall of the cochlea 

 on which it lies is called the basilar membrane, while the opposite 

 wall is spoken of as the memlrane of Beissner (Fig. 186): this is 

 already represented in Crocodiles and Birds. 



