144 REMARKABLE FOSSIL DEPOSITS NEAR BRISTOL. 



barrows and caves of Derbyshire says, "^ I never explored either a 

 burial mound or a cave without finding plenty of the remains of 

 the Water Vole. Indeed they come out by spadefuls." 



Although the Water Vole is often called the Water Rat, it is 

 not a true rat at all, but is more nearly related to the Beaver, both 

 in its anatomy and habits. 



The Beaver ( Caster fiber) has five toes on each foot, those of the 

 hinder feet webbed and has the tail flattened horizontally. It is 

 a true vegetable feeder, and in winter lives in an underground 

 habitation, nicely lined and very clean. 



The Vole {Arvicola amphibia) has five toes on the hinder feet, 

 but the fore feet have only four complete ones with a rudimentary 

 fifth or thumb. The teeth differ very materially from those of the 

 beaver and the rat. 



The curious incisor teeth deserve special attention. They are 

 covered with hard enamel on the convex side, so that as the bone 

 wears down much faster than the enamel, the extremity of the 

 teeth maintain a sharp cutting edge. The great length of the 

 incisors is remarkable in all the rodentia. Their shape resemble 

 the segment of a circle. The extremities of the fossil incisors 

 closely resemble those of the beaver, and are more chisel shaped 

 than those of the rat. Linnaeus was so struck with the habits of 

 the Arvicola and its affinity to the Beaver that in his "Fauna 

 suecica" he gave it the generic name of Castor. 



The Arvicola, like the Beaver, is a true vegetable feeder, is 

 scrupulously clean in its habits, and like the Beaver inhabits the 

 banks of streams and lakes. It has often been accused of being 

 destructive to fish, but this is a popular mistake, for on the contrary, 

 it is often devoured by Pike and Trout. In short the Arvicola may 

 be fairly taken as the English successor to the Beaver, which in 

 Britain has died out and quite disappeared. 



On the other hand the Rat (Mas decumanus) is well distinguished 

 from the Vole by being a true flesh eater, and is not very particular 

 in the quality of the flesh with which it meets, or in the cleanliness 



