AUDITORY BULLA IN THE MUSTELID.^. 



479 



forms, but horizontal or inclined slightly downwards towards the 

 inner wall of the cavity. It is thus nearer the periotic bone, and 

 diminishes the height of the passage between the anterior and 

 posterior portions of the bulla. 



Text-fi"ure 16. 



A. Bulla of Tayra harbara opened from behind. 

 ]}. The same of Gulo gulo. 

 C. The same of 3fartes martes. 

 T). The same oi ilartes foina . 



E. The same of Neles meles opened from below in front and behind. 



F. The same from behind. 



Lettering as in Text-fig. 1-5. 



Ltitra lutra, cinerea, haravg, and maculicollis have a very simple 

 type of bulla, differing from those described above in that the 

 tympanic ring, in conformity with the comparative flatness of 



pROC. ZooL. Soc - 1921. No. XXXIII. 33 



