280 THE MAMMALIA. 



It may, however, be remarked that our B ars 

 had representatives in the Miocene. In those times 

 there existed the Ampliicyon, of the size of a wolf, 

 but in reality a dog with p*, m 3 , the broad crowns 

 of the first two molars showing the incomings of 

 tubercles which point to a definite form of food. 

 This characteristic is even more marked in a later 

 form of bear-dog, Hyanarctos (p* y m 2 ), and has 

 preserved its full development in the bear (Ursus) 

 from the Pliocene up to the present period. How- 

 ever, the fewer number of teeth of the Hysenarctos 

 again forbids its being classed with the actual 

 ancestral line of the Bears. The latter with their 

 flat tuberculate molars, which point to a fixed food, 

 and their tolerably blunt carnassials, are compara- 

 tively a late modification, to a certain extent a 

 reversion to the beast of prey. This character 

 has, however, been retained by the polar bear, 

 which has again become a pure flesh- and fish- 

 eater. 



Gaudry has pointed out an ancestor for Hyaenas 

 in the genus Ictitherium from among the fauna 

 discovered at Pikermi. All that was required in 

 this animal to give its dentition the formula and 

 structure of that of the Hyaena, was the disappear- 

 ance of the second molar above and below (and the 



