1843.] . 283 



5. Containing more or less distinct traces of fossils, apparently from macerated 

 subjects. 



£x. gr. Vertebra; of cartilaginous fisb. 



Ex. gr. Crustacea, very numerous. N. B. Their remains in the Crag are 



never thus fossilised unless under coprolitic associations. 

 Ex. gr. Two echiniform masses. 



6. Various forms, more or less amorphous. 



7. With vermicular-like traces (Algaa?), as in the nodules from Green 

 sand and Gault. 



8. With pitted surfaces, as if from the escape of bubbles of gas. 



9. Ditto on fragments of cetaceous (?) bones highly polished, and perhaps 

 half digested. 



10. Another description of nodule, less common, larger and more gritty, often 

 containing organic matter, as shells, &c. 



4. Appendix to Professor Henslotv's Paper, consisting of a De- 

 scription of the Fossil Tympanic Bones referable to four 

 distinct Species of Bai,jen A. By Richard Owen, Esq., F.R.S., 

 Hunterian Professor in the Royal College of Surgeons. 



The fossils from the Crag at Felixstow, which have been sub- 

 mitted to my inspection by Professor Henslow, are the tympanic 

 portions of the petro-tympanic bones of large Cetacea. 



The tympanic adhering to the petrous portion by only two small 

 surfaces is easily detached, and may be recognised hj its con- 

 choidal shape and peculiarly dense texture ; the recent bone break- 

 ing with almost as sharp a fracture as the petrified fossils. 



None of these are entire : the thin brittle outer plate which 

 bends over the thick, rounded, and, as it were, involuted part, like 

 the outer lip of sucli simple univalves as the BuUce and Lepto- 

 concJii, is broken or worn away in the best specimens, all of which 

 are rolled and waterworn. 



We are led by the size of the specimens to the largest of the 

 existing Cetacea for the subjects of comparison, as the Grampus, 

 the Hyperoodon, the Cachalots {Physeter), and the true whales 

 {Balcenoptera and Balcenct). 



Tavo or three of the specimens are fortunately sufficiently entire 

 to show the form of the tympanic cavity bounded by the over- 

 arching plate, with the proportion and direction of its anterior or 

 Eustachian outlet, and most of them have the opposite or hinder 

 extremity entire. We are thus enabled to determine that the 

 majority differ from the tympanic bones of the Delphinidce, includ- 

 ing the Grampus and Hyperoodon, in having the hinder extremity 

 of the bone simple and not bilobed ; and some of them, in having 

 the anterior outlet of the cavity partially enclosed by the extension 

 of the outer plate around that end. 



With regard to the Cachalot {Physeter), I regret that I have had 

 no opportunity of comparing the Felixstow fossils with the tym- 

 panic bone in that genus, which I know only by the figures given 



