The Polar Bear has even been placed in a separate genus, Thalassarctos, a proceeding which is quite unnecessary. The white colour of this Bear tends to become browner with age. It is one of the few mammals which extend right round the pole; the Polar Bear is of course a purely Arctic animal. The chief food of the Polar Bear is Seal. Out of thirty Bears examined, Mr. Koettlitz found that only fifteen had animal remains in their stomachs, and these remains were invariably Seal. The animal apparently hunts by scent rather than by sight or hearing, both of which senses seem to be somewhat dull. The males and females wander separately, except of course during the breeding season. The Bears dig holes in which they may remain for some time, but there is no hibernation. In Pleistocene times, the Polar Bear extended as far south as Hamburg. The female has four mammae, pectoral in position.
Melursus includes only M. labiatus, the Sloth Bear of India. This animal has an upturned snout, which is described as closely resembling that of Mydaus, the Teledu. The snout has no groove.
All Bears are largely vegetarian and insect feeders; but this Bear is especially so. It delights in the nests of Termites, and its energy in destroying these hills for the sake of their inhabitants is so great that the name of "sloth" appeared to Sir Samuel Baker to be an entire misnomer.
Aeluropus, a rare Carnivore with but one species, A. melanoleucus, is not inferior in size to the Brown Bear, and is distinguished by its largely white coloration. It was discovered in the mountains of East Thibet by Père David, and described by Milne-Edwards[[304]] as a distinct and new genus, the discoverer himself having named it as a species of Ursus. It is a vegetable-feeding creature and bulky in form, with a rudimentary tail and a short broad head; in fact, more like a Bear than a Procyonid (with which group it is placed by some). The width of the head, however, is greater than in any other Carnivore; it is most closely approached in this by Aelurus and by Hyaena. The molar formula is Pm 4/3 M 2/3. The soles are hairy. There is no alisphenoid canal. The molars are especially large and multicuspid.
Fig. 226.—Aeluropus melanoleucus. × 1⁄12.
Fossil Ursidae.—The genus Ursus itself goes back to Pliocene times. The well-known Cave Bear, Ursus spelaeus of
Pleistocene times, was one of the commonest of Carnivorous creatures during the very early times of the present era. It was as huge as a Polar Bear or a Grizzly. The skull is remarkable for the fact that the first three premolars, which are small in all Bears, dropped out early in life. An immense number of names have been given to what are in all probability the same species as this Cave Bear of remote antiquity.
Hyaenarctos is the oldest genus of true Ursidae. It goes back into Middle Miocene times, and ranged over Europe and North Africa.
Arctotherium is an American genus of Pleistocene times. The likeness of some of the extinct Canidae to Bears has been already commented upon.