174 ME. E. T. NEWTON ON A SKULL OF TROGONTHERIUM CUVIERI 



7. Conclusions. 



To summarize in a few words the results of the above examination and comparison 

 of the skull from the Forest Bed of East Runton : — In the first place, there can be no 

 question that, although presenting many points of resemblance to the Beaver's skull, 

 the differences are nevertheless of greater importance, and indicate at least a generic 

 distinction. 



In the second place, this skull, in all its essential characters, agrees so closely with 

 the type of Trogontherinm cuvieri, described by M. Fischer, that there are no suiHcient 

 grounds for regarding them as representatives of more than one species ; the fossa in 

 the basioccipital bone of Fischer's type having been, as I believe, artificially produced. 



And thirdly, the skull from Saint-Prest, named Conodoutes boismllettn by M. Laugel, 

 also agrees so well with Fischer's type and with the Forest Bed skull that it must be 

 included with them in the same species. 



The earliest name given to this rodent was Trogomtherium cuvieri.; it does not appear, 

 however, in M. Fischer's first description of the skull, but seems to have been used by 

 him in a letter to Cuvier, who gave it in the heading of his article in the ' Ossemens 

 Fossiles,' but did not adopt it for the fossil. It was not until the year 1846 that 

 Sir E. Owen, in his ' British Fossil Mammak and Birds,' used this name for the English 

 Forest Bed specimens ; but fortunately the other generic and specific names proposed 

 for these fossils are of subsequent date, and cannot therefore be used. 



Bones of other parts of the skeleton, which, for cogent reasons, are believed to belong 

 to this rodent, have been found in the Cromer Forest Bed, and were described by 

 Sir R. Owen in the ' Geological Magazine' for 1869, and by the present writer, in the 

 'Vertebrata of the Forest Bed,' in 1882; no important additional specimens have 

 been obtained until the finding of the skull which has formed the subject of the 

 present communication. 



8, Bihliograp'hy.. 



1809. Fischer be Waldheim, Gotthtslf. Sur \' Elasmatherium et le Trogontherinm. Moscow Soc. 



Nat., Mem. voL ii. p. 250. 

 1824.-25. Cuvier, G. Reclierclies sur les Ossemens Fossiles. Edit. 3, vol. v, p. 59. 

 1833-34. SchmeisaLIng, P. C. Recherches sur les Oss.emens Fossiles decouiverts dans les Cavernes 



de la Province de Liege. 

 1840. Lyell, C. On tlie Boulder Formation or Drift and the associated Fxeshwater Deposits 



composing the Mnd-clifFs of Eastern Norfolk. Phil. Mag. ser. 3, vol. xvi, p. 345. 



1846. Owen, R. Britisli Fossil Mammals and Birds, p. 184. 



1847. RouiLLiER, C. Jnbilseum semissecularem Doctoris Gotthelf Fischer de Waldheim, celebrant 



Sodales Soc. cses. nat. scrut. mosquensis &c. 



1848. PoMEL, A. Diabroticus schmerlingi. Biblio. Univ. Geneve, Arehiv. Sci. vol. ix, p. 167. 

 1862. Laugel, A. Conodo?ites boisvillettii. Bull. Soc. Geol. France, ser. 2, vol. xis, p. 709. 

 1864. Lartet, E. Comptes Rendus, vol. 58, p. 1201. 



