146 THE SKULL. [chap. 



fits on to the petrosal and squamosal bones, and prolonged 

 externally into the much thickened spout-like floor of the 

 meatus externus. At the inner extremity of this floor is a 

 freely projecting oval lip (/), which gives attachment to the 

 membrana tympani, and which is the original and first ossified 

 ring-like portion of the tympanic bone. In the front of the 

 floor of the bulla is the groove for the Eustachian canal (e) \ 

 between this and the inferior part of the tympanic ring, 

 a low and thin ridge of bone with a concave free margin 

 rises from the floor of the cavity. This is the only 

 indication of any septum or division of the cavity of the 

 bulla. 



Behind the bulla, the prominent and tuberous paroccipital 

 process projects downwards, outwards and backwards, 

 standing quite off* from the bulla, and only connected with 

 it by a low laterally compressed ridge. Between the 

 paroccipital process and the occipital condyle is a smooth 

 concave surface, the front of which is excavated into a deep 

 notch, the posterior boundary of the foramen lacerum 

 postenus, between which and the condyle is situated the 

 condylar foramen, which transmits the hypoglossal nerve. 

 At the outside of the bulla, just behind the external auditory 

 meatus, the mastoid process is distinct and prominent, and 

 widely separated from the paroccipital. There is a very 

 conspicuous glenoid foramen situated just behind the post- 

 glenoid process of the squamosal. 



All the Ursidce, Procyofiidce, and Mustelidce agree with 

 the true Bears in the general characters of this region of 

 the skull; for even when (as in some of the smaller species) 

 the auditory bulla is considerably dilated, it always has its 

 greatest prominence near the middle of the inner border, and 

 gradually slopes away from this point to a prolonged floor of 

 the auditory meatus; and though there are often trabecular 



