34 
CARNIVORES. 
Extinct Bear-Like Genera. 
At the close of the preceding volume it has been mentioned, that, unlike 
as modern dogs and bears are to each other, yet both families are merely 
divergent branches from a common stock. In that passage we referred only 
to those extinct animals most nearly related to the modern dogs, and it was 
then shown that the so-called amphicyon of the Miocene and upper part of the 
Eocene period appeared to be a dog with one more pair of upper molar teeth 
than the true dogs, and approaching the bears in its plantigrade feet. We 
have now to allude to the extinct genera more nearly allied to the modern 
bears. The first of these is a bear-like animal from the superficial deposits of 
South America, known as the arctothere. This animal, of which the left side of 
the palate is shown on a greatly- 
reduced scale in the accompanying 
figure, had the same number of 
teeth as the true bears. The upper 
molar teeth (the two on the right 
side of the figure) are, however, 
relatively shorter and wider than 
in the latter, and the second is not 
greatly larger than the first. Then, 
again, the upper flesh - tooth (the 
third from the right in the figure) 
is much larger than in modern 
THE LEFT HALF OF THE UPPER JAW OF THE ARCTOTHERE— 
AN EXTINCT SOUTH AMERICAN BEAR - LIKE ANIMAL 
(much reduced). 
bears, and is thus more like the corresponding teeth of other Carnivores. Further, 
the upper arm-bone, or humerus, has a perforation at its lower end, which is not 
found in any living dog or bear, although occurring in the extinct amphicyon. 
Another type is the so-called hysenarctus, of which large species occur in the 
Siwalik Hills of India and the Pliocene deposits of Europe, while smaller ones are 
found in the European Miocene strata; the two upper molar 
teeth of one of the latter being shown in the accompanying 
woodcut. In these animals the upper molars (as in our 
illustration) were sometimes oblong, with the second not 
longer than the first; while, in other cases, they were more 
or less completely triangular, and thus but little different 
in form from the corresponding teeth of the dogs. The 
most important difference from the bears occurs, however, in 
the form of the flesh-tootli in both jaws; these teeth being 
very similar to those of the dogs, and of a thoroughly carnivorous type. Whereas, 
however, the upper flesh-tooth of the dogs has but two lobes to its cutting blade, 
that of the hysenarctus had three such lobes. That the hysenarctus was a 
thoroughly carnivorous animal, there can be no reasonable doubt. Another 
Miocene Carnivore, known as the hemicyon, has still more dog-like teeth; and 
the transition from this animal to the plantigrade and dog-like amphicyon is, 
therefore, scarcely more than a step, so that the passage from the dog-like bears to 
the bear-like dogs is practically complete. 
THE LEFT UPPER 
TEETH OF A 
SPECIES OF 
arctus.— After Kokeii. 
