382 



THE SENSORIAL FUNCTIONS. 



circular canals; while to the lower anterior side of 

 the vestibule there is attached a spiral canal, re- 

 sembling in appearance the shell of a snail, and on 

 that account denominated the Cochlea (k). All 

 these bony cavities are lined with a very delicate 

 membrane, or periosteum^ and are filled with a 

 transparent watery, or thin gelatinous fluid, which 

 is termed by Breschet the perilymph* 



Within the cavity of the osseous labyrinth now 



described, are contained membranes having nearly 

 the shape of the vestibule and semicircular canals, 



* Recherches Anatomiques et Physiologiques sur I'organe de 

 I'ouie et de I'audition dans I'Homme et les Animaux vertebres. 

 Paris, 1836. It has also been called the Aqua labyrinthi, and the 

 fiuid of Cotunnius, from the name of the Anatomist who first dis- 

 tinctly described it. 



