132 BRITISH MAMMALS 



such as the absence of a cascum, and of an entepicondylar foramen 

 (see p. 149), the presence of a long penial bone, and other 

 peculiarities of the male genital organs, and a rudimentary tail. 

 They possess the same number of teeth as the typical dog 

 (though in one genus there is the occasional loss of one pair of 

 incisor teeth in the upper jaw). Yet there is a tendency in the 

 first two premolars in the upper and lower jaw to disappear. 

 This gives the skull of a bear, therefore, an aspect very different 

 from the skull of a dog, as it induces (when the premolars have 

 dropped out) a large diastema, or toothless space, between the 

 great canines on the one hand and the molars on the other. 

 Nevertheless, in modern bears (as opposed to many extinct 

 genera) all four premolars are represented in both jaws, however 

 rudimentary may be the first three. The fourth, or carnassial, 

 tooth in the upper jaw is proportionately smaller than in the 

 dogs, is blunter, and of little importance as a tearing tooth. 

 This is, no doubt, partly due to degeneration. The molar teeth 

 are large as compared with those of the dog, and have broad, flat, 

 tuberculated crowns. The canine develops into a considerable 

 tusk. The number of teats is usually three pairs, one pair 

 situated on the breast and two pairs along the belly. 



The bears, like so many other groups of mammals, seem to 

 have arisen in India, or on the northern limits of that country, 

 where the remains of the first true bear are found in Upper 

 Miocene strata. In Europe they made their appearance in the 

 Upper Pliocene, and the earlier forms of European bear agreed 

 with the brown bear of to-day in possessing four premolars in 

 both upper and lower jaw. 



Ursus arctos. The Brown Bear 



This species is, in some respects, the least specialised amongst 

 existing bears. Its colour ranges from dark fulvous-brown to 

 silvery-gray. Young bears have white on the throat — a detail 

 of coloration which is seen in other species and genera of bears, 

 and in members of the Weasel group. In Eastern Tibet the 

 brown bear tends towards black in coloration on the upper parts. 



