168 
. MR. TOYNBEE ON THE MEMBRANA TYMPANI. 
and it shows that the six layers of which it is composed are continuous with adjacent 
tissues. 
I may state in conclusion, that the opinion of the non-muscularity of the fibrous 
laminae of themembrana advanced in the above paper, has been confirmed by 
Dr. Harrison of Dublin, in his dissection of the memhrana tympani of the Elephant ; 
he says, “ I see no evidence of the muscular structure of the membrana tympani, so 
accurately described by Sir Everard Home in the Philosophical Transactions, and 
mentioned by subsequent writers, who seem to have adopted his opinions rattier than 
to have examined the organ for themselves*.” 
Explanation ofjigure 17, showing the six Lamince composing the Memhrana Tympani. 
A vertical section from without inwards of the meatus externus, membrana tympani 
and cavitas tympani. 
M. E. Section of the meatus externus. 
C. T. Section of the cavitas tympani. 
M. T. Section of the membrana tympani. 
a. The epidermis lining the meatus externus. 
h. The dermoid layer of the meatus externus. 
c. The periosteum of the meatus externus. 
d. The periosteum of the tympanic cavity. 
e. The mucous membrane of the tympanic cavity. 
f. The epithelium of the tympanic cavity. 
g. The circular fibro-cartilage of the membrana tympani. 
* Anatomical Observations on some Parts of the Elephant, by Robert Harrison, M.D., Professor of Ana- 
tomy, Trinity College, Dublin. Proceedings of the Royal Irish Society, vol. iii. 
18 Savile Row. 
