DOGS AND BEARS. 195 



size of a bear, but had teeth like those of a dog, although 

 it was in all probability plantigrade, and it had a per- 

 forated arm-bone. Here, then, we have at length 

 reached an animal where our definition of a dog and 

 a bear begins to fail us, in spite of the "stretching" 

 we have given these definitions when discussing the 

 hyaena-bear. Yet one step still further back to the 

 lower part of the Miocene and the upper part of the 

 preceding or Eocene epoch the dawn of the Tertiary 

 period and we find an animal, the so-called Amphi- 

 cyon in regard to which it appears to be impossible to 

 say whether it partakes most of the nature of a dog or 

 of a bear. The best known species of the amphicyon was 

 of the approximate dimensions of a wolf, but others 

 were larger. They had teeth more especially the 

 "flesh-teeth" (Fig. 60) precisely like those of a dog, 

 with the exception that there were three in place of 

 two grinders in the upper jaw, and the general build 

 was also dog-like, with a perforation in the lower end 

 of the arm-bone. The skull has, however, the bladder- 

 like "bulla" of the dogs, but the animal applied the 

 whole soles of its feet to the ground in walking after 

 the old-fashioned plantigrade manner, and made no 

 attempt to assume the more advanced digitigrade pro- 

 gression of the dogs. 



Here, then, it is evident that we have to do with an 

 animal that is quite as much a dog as a bear, being, in 

 fact, a veritable " missing-link ; " and consequently a 

 source of sad trouble to those systematists who wish 

 to assign everv creature to a fixed place in their cut- 



