288 



1447. The mutilated body of a petrified vertebra of a coarse osseous texture, 



apparently Cetacean. 



Locality unrecorded. Hunterian. 



1448. A cast of the tympanic portion of the petro-tym panic bone of a Whale 

 (Balcena affinis, Owen). The specimen measures five inches in length, 

 and resembles the tympanic bone of the Balcena antarctica in the slight 

 elevation of the posterior part of the involuted convexity, and its gra- 

 dual diminution to the Eustachian end of the cavity : it resembles the 

 tympanic bone of both the Balcena antarctica and the Bal. mysticetus 

 in the gradual continuation of the concave outer wall from the in- 

 voluted convexity : this convexity is indented also, as in both the 

 recent species of Balcena, by vertical fissures, narrower than the marked 

 indentation which distinguishes that part in the Bal. mysticetus : the 

 upper surface of the fossil tympanic bone maintains a more equable 

 breadth from the posterior to the anterior end, the outer angle of which 

 is salient in the fossil, but is rounded off in the recent specimens : the 

 under and outer surfaces of the fossil tympanic bone meet at an acute 

 angle. Having found the above characters sufficiently marked in three 

 specimens of fossil tympanic bones, I have regarded them as indicative 

 of a species distinct from the known existing Balance, but most nearly 

 allied to the Bal. antarctica*. 



From the red crag at Felixstow, Suffolk. 



Presented by the Rev. Prof. Henslow, F.R.S. 



1449. A portion of the right tympanic bone of the Balana ajffinis, from which 



almost the whole of the free over-arching plate has been broken away. 

 From the red crag at Felixstow, Suffolk. 



Presented by the Rev, Prof. Henslow, F.R.S. 



1450. The tympanic bone of the Balcena mysticetus, with part of the over- 



arching plate sawed off, showing the density of its structure, and affording: 

 a means of comparison with the fossils. The difference in the breadth 

 of the anterior end of the bone, between the recent and fossil specimens, 

 is well marked. 



* Proceedings of the Geological Society, December, 1S43. 



