AUDITORY BULLA IN THE JIUSTELID/E. 



Text-figure 15, 



477 



A. Part of the skull of Lutra hitra sliovving the abnormal occun-ence of the 



alisphenoicl canal indicated by arrow. 



B. Bulla of Selicti.i everetti, the posterior chamber opened from behind showing 



the partition (pt.) descending to the petrous. 



C. The same from below cut open to show the partition (pt.) running obliquely 



between the anterior chamber (a) and the posterior chamber (h). 



D. Bulla of Putorius putorius opened from behind, showing the thickened spongy 



tissue of the walls and the undivided cavity. 



E. Bulla of Lutra lutra showing the partial division of the cavity bj' rafters. 



F. The same fi'om below. 



Lettering : — a, h, anterior and posterior chambers of cavity (in B, C) ; //, glenoid 

 foramen ; o, foramen ovale ; p, petrous portion of periotic ; po, paroccipital 

 process; pt, partition (in B, C) ; r, rafter; t, edge of tympanic annulus. 



