174 MR. E. T. NEWTON ON A SKULL OF TROGONTHERIUM CUVlEfil 



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 Tivf/ontherium cuvieri, described by M. Fischer, that there are no sufficient 

 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 Conodontes hoisviUettii 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 Trog anther mm 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 R. Owen, in his ' British Fossil Mammals 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 wliich lias formed the subject of the 

 present comm-unication. 



8. BilUographij. 



!809. Fischer de Wjldheim, Gotthklf. Sur V Elasmotherium et le Trogontherlum. Moscow Soc. 



Nat., Mem. vol. ii. p. 250. 

 1824-25. CuviER, G. Recherches sur les Ossemens Fossiles. Edit. 3, vol. v, p. 5i). 

 1833-34. ScHiiERLiNG, P. C. Reehorchos sur les Ossemens Fossiles decouvei'ts daus les Cavernes 



de la Province de Liege. 

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



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



1846. Owen, R. Britisli Fossil Mammals and Birds, p. 181-. 



1847. RuniLLiER, C. Jubiliieum semissecularem Doctoris Gotthelf Fischer de Waldheim, celebrant 



Sodales !Soc. cses. nat. scrut. mosquensis &o. 



1848. PoMEi-, A. Diabroiicus schmerlinffi. Biblio. Univ. Geneve, Archiv. Sci. vol. ix, p. 167. 



1863. Laugel, A. Conodontes boisvUkttii. Bull. Soc. Ge'ol. France, ser. 2, vol. xis, p. 709. 



1864. L.\RTET, E. Comptes Rendus, vol. 58, p. 1201. 



