196 CASTORIDJE. 



John Hunter had obtained, from a moss-pit in Berkshire, 

 the upper jaw and the right ramus of the lower jaw of a 

 Beaver. These are rather smaller, and belonged to a 

 younger animal than the Cambridgeshire specimens ; but 

 the portion of the skull exemplifies the character of the 

 European Beaver, in the extension of the nasal bones to 

 beyond the middle of the orbits. This character is also 

 well shown in the skull of a Beaver more recently disin- 

 terred from the fens of Cambridgeshire, and figured at the 

 head of the present section. The transverse line touching 

 the point of the nasal bones, intersects the orbits behind 

 their middle part; in the Canadian Beaver the transverse 

 line touching the same points of the nasal bones, usually 

 intersects the antorbital processes. In the view of the base 

 of the skull {fig. 74) the complex inflections of the enamel 

 upon the grinding surface of the molar teeth is shown. A 

 very characteristic part of the skull of the Beaver was, 

 however, lost in the specimen figured. In an entire skull 

 recovered, with a great part of the skeleton, from the Cam- 

 bridgeshire fens, and now in the museum of Professor Sedg- 

 wick, the character alluded to is well shown. It is mani- 

 fested in the basilar process of the occipital bone, which 

 has a peculiar cavity on the under and outer surface, as if the 

 bone had been pressed upwards when soft, or indented by 

 the end of a finger. This cavity lodges a peculiar sac 

 of the pharynx in the recent animal ; some additional 

 lubrication is perhaps requisite to facilitate the deglutition 

 of the coarse vegetable substances which chiefly consti- 

 tute the food of the Beaver. This cavity is both deeper 

 and wider in the old British Beaver, than in the Canada 

 species. The following are the dimensions of the skull 

 above-cited, from the Cambridge fens : 



