8 MR. W. H. FLOWER ON THE (Jan. 14, 
which is the original and first ossified ring-like portion of the tym- 
panic bone. In the front of the floor of the bulla is the groove for the 
eustachian canal (e) ; between this and the anterior part of the tym- 
panic ring, a low and thin ridge of bone with a concave free margin 
rises from the floor of the eavity. This is the only indication of any 
septum or division of the cavity of the bulla. Whether the whole 
of this bone is developed from the original tympanic, or whether the 
bullate inner portion 1s (as will be shown to be the case in some other 
Carnivora) ossified from a distinct cartilage of its own, I am not at 
present able to determine. In the youngest Bears’ skulls that I have 
examined, the ossification of the whole bulla is continuous with that 
of the tympanic ring and floor of the meatus. 
Fig. 2. 
Section through the auditory bulla of Ursus ferox. 
Sq. Squamosal bone. ZT. Tympanic bone. BO. Basioccipital. g. Glenoid 
canal. a.m. External auditory meatus. ¢. Tympanicring. e. Eustachian 
canal. car. Carotid canal. 
Behind the bulla (fig. 1, p. 7) the prominent and tuberous paroc- 
cipital process (p) 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 posticum (1), between which and the condyle is the distinct 
subcircular foramen condyloideum (¢), which transmits the hypo- 
glossal nerve. 
At the outer side of the bulla, just behind the meatus auditorius 
externus, the mastoid process (m) is distinct and prominent, and 
widely separated from the paroccipital. At the bottom of a deep 
