48 FACULTIES OF BIRDS. 



human ear, and like it fitting the oval hole, to which 

 it is braced all round by a very slender membrane*. 



M. De Blainville, in opposition to most other 

 comparative anatomists, and in conformity to the 

 doctrine of minute analogies now pursued on the 

 Continent, endeavours to show that the chain of 

 bones found in the human ear is equally to be found 

 in r birds, though in order to make out this, he is 

 under the necessity of confessing that, while " the 

 chain of small bones is complete," these bones con- 

 sist not of bony substance, but of cartilage, sub- 

 cartilage, and even of muscles j\ 



With reference to this speculative theory upon the 

 subject of the ear of birds, Sir Charles Bell, justly 

 remarks, that " the only effect of this hypothesis is 

 to make us lose sight of the principle which ought 

 to direct us in the observation of such curious 

 structures, as well as of the conclusions to which an 

 unbiassed mind would come. The matter to be ex- 

 plained is simply this : the chain of bones in the 

 ear, which is so curiously adapted in the mammalia, 

 to convey the vibrations of the membrane of the 

 tympanum to the nerve of hearing, is not found in 

 the organ of hearing of birds ; but there is substi- 

 tuted a mechanism entirely different. They choose 

 to say that the incus, one of the bones of the chain, 

 is wanting in the bird. Where shall we find it? 

 they ask. Here it is in the apparatus of the jaw or 

 mandible ; in that bone which is called 05 qua- 

 dratum. I believe that the slight and accidental re- 

 semblance which this bone in the bird has to the incus 

 is the real origin of this fancy. Let us follow ajuster 

 mode of reasoning, and see how this hypothesis ob- 

 scures the beauty of the subject. The first step of 

 the investigation ought to be to inquire into the fact, 



*Cuvier, Lecons d'Anat. Comp. Blumenb.; Derham ; Phys. 

 Theol. vii. 2, note d. 



f Principes, p, 527. 



