URSUS SPEL^US. 



107 



middle, or miocene tertiary formations, through the older 

 and newer pliocene, and that the genus surviving, or under 

 a new specific form reappearing after the epoch of the depo- 

 sition and dispersion of those enormous, unstratified, super- 

 ficial accumulations of marine and freshwater shingle and 

 gravel, called drift and diluvium, has been continued 

 during the formation of vast fens and turbaries upon the 

 present surface of the island, and until the multiplication 

 and advancement of the human race introduced a new cause 

 of extermination, under the powerful influence of which 

 the Bear was finally swept away from the indigenous 

 Fauna of Great Britain. 



The adjoining figures illustrate the characters derivable 

 from the lower jaw and its dentition, of three, of the species 

 by which the genus has been represented in England, 

 during the different periods above cited, o, jig. 35, is the 

 jaw of the extinct Ursus spelaus, from the Norfolk pliocene ; 

 it shows the complex premolar (3 p) and the long toothless 

 interval between it and the canine : B is the jaw of the 

 Ursus priscus of the post-pliocene epoch, in which the inter- 

 val is shorter and retains the first small premolar (1 p) : A 

 is the jaw of the Ursus Arctos from the Cambridge fen, 

 in which the shorter interval retains two small premolars, 

 and the third (3 p) has a more simple crown. 



With the present experience of physiologists as to the 

 range of variety of which a specific form is susceptible, 

 through the long continued operation of external influences, 

 we cannot attribute the anatomical differences which have 

 been pointed out in the fossil teeth and bones of Bears derived 

 from the above-cited series of formations, to varieties of one 

 species produced by such accidental causes. On the con- 

 trary, those Bears which existed anterior to the present con- 

 dition of the surface of the British Islands must be referred 

 to two species distinct from any now known, and which have 



