330 Mr. R. I. Pocock on the Auditory Bulla 
towards the inner angle of the anterior edge of the bulla. 
The outer chamber extends slightly more forwards than the 
anterior end of the inner chamber, which in front forms a 
narrow passage between the partition and the wall of the 
Felis sylvestris. (Scotland.) 
A. Base of skull, from below, with inner chamber of right bulla laid open. 
B. Right bulla of the same, from inner side. 
C. The same, from outer side. 
p-, partition; x., periotic; p.’, line of origin of partition. 
bulla owing to the encroachment of the partition on the - 
chamber at this point. The bull of two specimens of 
F. canadensis (fig. 3) differ rather unexpectedly from those 
