X.] 



CARNIVORA. 



147 



or partial septa passing mostly transversely across the lower 

 part/ there is no distinct and definite septum dividing it 

 into a separate outer and inner chamber. In all cases, on 

 looking into the external auditory meatus (in the dried 

 skull when the membrana tympani is removed) the oppo- 

 site wall of the bulla can be seen ; or if a probe is passed 

 into the meatus, no obstacle will prevent its touching the 

 inner wall. 



Fig. 53. — Section of the left auditory bulla of the Tiger {Felis ti^ris). Sq squa- 

 mosal ; Pt periotic; BO basioccipiial ; am external auditory meatus ; oc the outer 

 chamber ; ic the inner chamber : 5 the septum ; * the aperture of communication 

 between the chambers. (From Proc. Zool. Soc. 1S69.) 



In the Tiger, which may be taken as a type of the Fclidcc, 

 the auditory bulla is very prominent, rounded and smooth 

 on the surface, rather longer from before backwards than 

 transversely, its greatest prominence being rather to the 

 inner side of the centre. The lower lip of the external 

 auditory meatus is extremely short; the meatus, in fact, 



^ Especially developed in the Weasels {Mustela), in which also Ihe 

 entire parietes of the bulla are thickened and cancellous. 



L 2 



