431 
1902-3.] Sir William Turner on the Sperm Whale. 
included, the breadth would be increased to 52 mm. From its 
posterior end an irregular, strongly denticulated piece of bone, 
which was closely fused by a broad base with the bulla, projected 
backwards as a pair of fork-like processes; between the two 
forks, and in relation to their deep aspect, was a furrowed surface, 
convex from before backwards, and concave from side to side, with 
which the posterior end of the petrous-temporal articulated. In 
the bulla itself the inferior surface was bilobed at and near the 
posterior end, and the outer lobe was larger and projected farther 
back than the inner; a distinct but not a deep groove, which 
extended obliquely across a part of this surface, marked the separa- 
tion between two lobes ; this surface was smooth in the greater 
part of its extent. The outer surface was also smooth, and ended 
in a sharp border which bounded the mouth of the tympanic bulla. 
A strong ridge sprang from this surface close to its posterior end, 
