CETOTOLITES. Dak 
characters are sufficiently marked in the specimens of the 
fossil tympanic bones, to justify their being regarded as 
belonging to a species distinct from the known existing 
Balene, but nearest allied to the Bal. antarctica, and 
which I propose to call Balena affinis. 
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Tympanic bone of Balena definita, 3 nat. size, Felixstow. 
A second species is characterised by the distinct defini- 
tion of the involuted convexity (a); and the extent of the 
slightly concave surface extending from it to the commence- 
ment of the overarching wall (4) ; the anterior extremity of 
the involuted convexity is equally well defined, and a wide 
concavity divides it from the anterior extremity of the 
Eustachian outlet (0). The thickest part of the involuted 
convexity is not very prominent. The under and outer 
surfaces of the bone meet at a right angle. 
The species indicated by the tympanic bones of this form 
I have termed Balena definita. 
MM 2 
