850 ////: M'i:ii;.\Ti s <>r Tin 



3. Adipose Cushion of the Krlminl Kar. 



This cushion, which is iicvcr absent, even in the most emaciated animals, 

 enrelops the base of the concha in front, inwardly, and posteriorly. It 

 facilitates the movements of that organ. 



4. Integuments of the External Ear. 



The skin covering the concha is covered with fine close hairs. That 

 lining its interior is very thin and vascular, adheres closely to the cartilage, 

 and is furnished with long silky hairs, to prevent the entrance of dust into 

 the ear. 



DIFFERENTIAL CHARACTERS IX THE AUDITORY APPARATUS OF OTHER THAN SOI.IITH 



ANIMALS. 



There are no notable differences in thn internal ear. 



In the middle ear, there are some modifications, either in the bones or accessory parts. 

 In Ruminants, the auditory bones are like those of the Horse, except that the handle of 

 the malleus is more curved, find the body of the incus is longer. In the Dog, tin handle 

 of the malleus is covered with small, pointed processes, and the Iranclie* <</' il/n *!, 

 long and thick. In the Pig, the brunches of the latter arc slight and inflect*-'!, and the 

 base is wide and thin : in a word, the stapes of this animal bears no rest-mblane. 

 stirrup; the malleus is very much inflected forwards. In the last two animals, no o- 

 nucleus is found in the tendon of the stapediun muscle. 



It is needless to say that the fenestia ovulis varies with the base of the stajn s. (The 

 absence of the mastoid cells in the Sh?e/> and (lout has been already noted.) 



The KndiK-hian tube exists in all the animals, but the guttural jiouchea are only 

 found in Solipeds. 



In the external ear, the conchal cartilage varies much in shape. It is thin, inclim-d 

 outwards, and widely c>iewd in linminnnl*. In the 1'ig, it dill'ers a littli-, according t 

 breed, though it is always much developed, sometimes erect. Imt must frequently 

 drooping. It is always short, pointed, erect, and open in front, in the ('(it. (In tliis 

 animal a small duplicature of the external margin of the concha is often seen.) In Jfinix, 

 the external ear is limited to the auditory canal. 



(The differences in the muscular arrangement have been noted elsewhere.) 



COMPARISON BETWEEN THE AUDITORY APPARATUS IN MAN AND THAT OF ANIMALS. 



There is nothing to be said regarding the internal ear. The middle ear com| 

 the same parts as that of mammifers other than Solipeds. The handle of the mull' .< i.s 

 straiy;hter, the incus more voluminous, and the stapes thinner, pro|>orti<>i.:iti-]y, tha-i in 

 animals. There is no bony nucleus in the stapedian muscle. The muscle of /// in<ill,-u* 

 is lodged in a distinct canal belonging to the Kustachiati tube. 



The external ear is composed of only two cartilages : one, forming the b-ise of t la- 

 concha, represents that cartilage in animals; tlie other, belonging to the auditory canal, 

 resembles the annular cartilage in the Horse. The concha is very irregular in .-hape, and 

 stands at an angle of from 15 to 45 from the temporal bone; it is convex su|ieri<>rly, 

 and terminates iuferiorly by a small lobe. On its anterior face it presents prominences 

 and depressions; the former are four in number: the helix, a. fold encircling tli 

 behind and above; the antihelix, a concentric prominence, almost parallel \\i(h tin- 

 preceding; the tragux, a triangular, pointed process, covered with hair, situated in front 

 of the auditory canal (meatus) ; the anfilragus, opposite the tiagus, In-hind the canal, 

 and above the lobule. The depressions are: the concha, a wide cavity. limited l.y the 

 antihelix ; the scaphoid fossa (fossa innominala) situated above the latter; and the /MM 

 triangularis comprised between the helix and antihelix. 



The pavilion of the ear is traversed by several muscular fasciculi, which ran have no 

 influence, on its movements. The concha has also extrinsic mn.-'-les the nnt< /// ourf- 

 eularis (attrahens aurem , aurirularis >///-// (atlolens aun'in), and tho <///,/, 

 posteriores (retrahens aurem). The action of these on the concha i.s very slight. 



