on the Membrana Tympani. 19 



The cochlea and semicircular canals must be considered as 

 two of the most important parts of the ear ; their peculiar forms 

 are no doubt adapted to some essential purposes ; but, what are 

 the precise advantages derived from their particular shape, is at 

 present unknown. There is, however, much ground to believe, 

 that a more extensive knowledge in comparative anatomy, join- 

 ed with future observations, may clear up this very curious and 

 obscure part of the physiology of the organ of hearing. 



In the elephant, the small bones, the cochlea, and semicircu- 

 lar canals, are larger than those in the human ear, nearly in the 

 same proportion with the increased size of the membrana tym- 

 pani. In that animal, there is a very remarkable peculiarity ; 

 which is, a cellular structure occupying the upper and posterior 

 part of the skull, inclosed between the two tables, communi- 

 cating by a considerable aperture with the cavity of the tympa- 

 num, and lined by a similar membrane: the cells commu- 

 nicate freely with one another at their lower extremities, but 

 not near the upper, forming irregular, cylinders, placed in a 

 converging direction, towards the cavity of the tympanum. 



There is no middle bony septum, separating the cells of the 

 skull belonging to one ear from those which open into the 

 other, but a ready communication between them. 



On the anterior part of the skull there is also a similar cel- 

 lular structure, only much smaller, which communicates with 

 the nose, but is entirely separate and distinct from that which 

 forms an appendage to the organ of hearing. 



That the elephant hears better than other animals, is gene- 

 rally asserted by those who have had opportunities of making 

 observations on the subject. As this opinion has been ad- 

 vanced by men who had no knowledge in anatomy, and had 



D2 



