16 MR. W. H. FLOWER ON THE [Jan. 14, 
porting the membrana tympani, and developed originally in mem- 
brane. Ossification extends from this, so as to complete the outer 
chamber and the very limited lip of the meatus auditorius externus. 
The inner chamber is formed from a distinct piece of hyaline carti- 
lage, which at birth is a narrow slip, pointed at each end, lying be- 
tween the tympanic ring and the basioccipital, applied closely to 
Fig. 5. 
Part of the base of the skull of the Tiger (Felis tigris). A portion of the audi- 
tory bulla has been removed to show its interior. The cavity of the inner 
or posterior chamber is exposed. 
ry. The fenestra rotunda in the petrosal. s. The septum between the chambers. 
x The aperture of communication. The other letters as in the preceding 
figures. 
