APPENDIX. 659 



anterior end, where the Eustachian tube begins. 

 The whole function of the Eustachian tube is 

 perhaps not known ; but it is evidently a duct 

 from the cavity of the ear, or a passage to the 

 mucus of those parts : the external opening hav- 

 ing a peculiar form, would lead us to believe that 

 something was conveyed to the tympanum. 



The part containing the tympanum is a thin 

 bone, coiled upon itself, attached by one end to 

 the portion which contains the organ ; and this 

 attachment in some is by close contact only, as 

 in the Narwhal ; in others the bones run into one 

 another, as in the Bottle-nose and Piked Whales. 



The immediate organ of hearing is contained 

 in a round bony process, and consists of the 

 cochlea and semicircular canals, which somewhat 

 resemble the quadruped ; but besides the two 

 spiral turns of the cochlea, there is a third, which 

 makes a ridge within that continued from the 

 foramen rotund um, and follows the turns of the 

 canaL 



The eye in this tribe of animals is constructed 

 upon nearly the same principle as that of quadru- 

 peds, differing however in some circumstances ; 

 by which it is probably better adapted to see in 

 the medium through which the light is to pass. 

 The crystalline humour resembles that of a qua- 

 druped, but whether it is very convex, or flat- 

 tened, I cannot determine; those I have exa- 



