290 



1454. A cast of a mutilated left tympanic bone of the Baleena emarginata, 

 Owen. This fossil differs from the last specimen in the less degree of 

 convexity of the involuted part, but more particularly in its outer border 

 being notched or indented, as in the Baleena mysticetus, by a vertical 

 angular impression, deeper and wider than the smaller vertical fissures 

 (see No. 1450). The comparative shortness of the involuted convexity 

 distinguishes this species from the Baleena affinis, the vertical notch and 

 the minor convexity of the involution distinguish it from the Baleena 

 gibbosa, and the immediate rising of the overarching wall, beyond the 

 inner boundary of the involution, from the Baleena definita. 

 From the red crag at Felixstow, Suffolk. 



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



All the more perfect ' cetotolites,' as the foregoing fossils have been 

 termed, which have shown the form of the tympanic cavity bounded 

 by the overarching thin plate, and at the same time the proportion 

 and direction of the anterior or Eustachian outlet, and above all the 

 larger or posterior end of the bone, have demonstrated their difference 

 from the tympanic bone in the Grampus, Hyperoodon and other larger 

 Delphinidce, inasmuch as these Cetaceans have the posterior end of the 

 tympanic bone bilobed, and not entire or simple as in the fossils, and 

 they likewise have the anterior outlet of the tympanic cavity partially 

 inclosed by the extension of the outer plate around that end. With 

 regard to the Cachalot (Physeter), I have had no opportunity of com- 

 paring the Felixstow fossils with the tympanic bone in that genus, 

 except by means of the figures of it, given by Camper* in his usual 

 spirited but sketchy style : Cuvier, who founds his notice of the 

 tympanic bones of the Cachalot on the same figures, states that they 

 most resemble those of the Delphinidce, but are less elongated and less 

 bilobed posteriorly. The figures show still more clearly that the tym- 

 panic cavity is continued freely forward out of the anterior end of the 

 bone, and terminates by a relatively wider outlet than in the Delphinidce. 



* Anatomie des Cetaces, plate xxiii. 



