35 



Order RODENTIA. 



Genus Castor. 



211. The anterior part of the skull, wanting the nasal bones, of a Beaver 



{Castor europceus, Ow., Castor fossilis, Goldf.). The incisors are 

 broken : three anterior molars remain in place on the right side : the 

 first is the deciduous molar, and is retained in the socket by three diva- 

 ricating fangs, in the interspace of which the crown of the permanent 

 successor is exposed on the left side. The specimen has therefore be- 

 longed to an immature animal. Jt was discovered in a moss-pit in 

 Berkshire. Hunterian. 



21 1 1 . The cranium of an American Beaver [Castor Canadensis, Kuhl), with 

 the nasal bones removed, for comparison with the fossil. College. 



A transverse line has been drawn across the anterior orbital processes 

 of the frontal bone, in the recent and fossil specimens, to illustrate the 

 osteological difference pointed out by Cuvier (Ossemens Fossiles, 4to, 

 1823, p. 57) between the Beaver of Europe and that of America; viz. 

 that the nasal bones extend beyond that line further in the European 

 than in the Canadian species : the present fossil agrees with the European 

 Beaver in this character ; but the species has long been extinct in Great 

 Britain. 



212. The right ramus of the lower jaw of a fossil Beaver {Castor europceus). 



From a moss-pit in Berkshire. Hunterian. 



Genus Trogontherium. 



213. The right incisor of the lower jaw of the gigantic fossil Beaver (Trogon- 

 therium Cuvieri, Fischer). This specimen is No. r. 21. of the Hunterian 

 Catalogue, and is described as " a long cutter of the scalpris-dentata, or 

 Glires genus"). The locality is not indicated, but fossils of the same 

 genus occur in the Norfolk Crag. Hunterian. 



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