196 CASTORID #. 
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 im 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 : 
EEE 
