TJKSDS -285 



upper premolar and first lower molar scarcely differentiated as 

 carnassials, the former 2-rooted, its inner lobe at posterior border 

 of crown, its position so far anterior to level of antborbital 

 foramen as not to be at point of greatest mechanical efficiency ; 

 auditory bulla flattened, without septum ; form heavy ; size 

 large ; feet strictly plantigrade ; digits, 5-5. 



Remarks. — The family Ursidse, containing the bears, is at 

 present represented by five or six genera, though the fossil 

 remains of others are known. The members of the group are so 

 easily recognizable by the peculiarities of the cheek-teeth that 

 they require no special comparisons with other carnivora. Two 

 genera occur in Europe. 



KEY TO THE EUROPEAN GENERA OP URSIDM. 



Cheek-teeth relatively large ; incisors and canines not 



specially enlarged and prehensive (Ordinary Bears) Ursus, p. 285. 



Cheek-teeth relatively small ; incisors and canines 

 enlarged and unusually^ prehensive in character 

 (Polar Bears) .' Thalarctos, p. 297. 



Genus URSUS Linnaeus. 



1758. Ursus Linnaeus, Syst. Nat., I, 10th ed., p. 47 (arctos, by tautonymy). 

 1857. Ursus Blasius, Saugethiere Deutschlands, p. 196. 

 1864. Euarctos Gray, Proc. Zool. Soc. London, p. 692 (americanus). 

 1864. Myrmarctos Gray, Proc. Zool. Soc. London, p. 694 (eversmanni = arctos) . 

 1898. Ursarctos Heude, Mem. Hist. Nat. Emp. Chinois, iv, pt. i, p. 18 

 sis). 



Type species. — Ursus arctos Linnseus. 



Geographical distribution. — Northern hemisphere from northern 

 limits of the great continental areas south to the Atlas Moun- 

 tains, the Himalayas and Mexico. 



Characters. — Dental formula : i *"*, c J"J, pm ", m £§ = 42 ; 

 inner upper incisor well developed, permanent ; first, second and 

 third premolars in both jaws small, single-rooted, readily deciduous, 

 especially pm 2 , pm 2 and pm 3 ; molars large and robust, the length 

 of the two upper teeth together equal to width of palate. 



Remarks. — The genus Ursus as thus restricted is a very 

 homogeneous group practically confined to the north temperate 

 region. The species are at present so imperfectly known that no 

 fair estimate can be made of their number. Recently about 

 thirty forms have been recognized, only one of which is definitely 

 known to occur in Europe. 



URSUS ARCTOS Linnseus. 



1758. [Ursus] arctos Linnaeus, Syst. Nat.,*i, 10th ed., p. 47 (Sweden). 

 1772. [Ursus] ursus Boddaert, Kortbegrip van het zamenstel der Natuur, 



i, p. 46 (Renaming of arctos). 

 1788. [Ursus arctos] a niger Gmelin, Syst. Nat., I, 13th ed., p. 100 



(Northern Europe). 



