502 CARNIVORES. 



blade of the sectorial ; the internal tubercle is developed from the 

 whole of the inner side of the base of the blade ; in the Ursus arctos 

 it is of a triangular form and supports a single obtuse eminence ; 

 in the Ursus maritimus the internal tubercle is smaller and is de- 

 veloped from the posterior half of the inner base of the blade : the 

 outer part of the fourth upper premolar is supported by two fangs, 

 and a third short rudimental one is developed from the inner tu- 

 bercle. The first upper true molar (ib. fig. 3 & 4, m 1) makes its 

 appearance^ above the gum, as usual, before the deciduous molars 

 are lost ; it has a large oblong quadricuspid crown with smaller 

 irregularities, and is supported by three roots. The second upper 

 true molar (ib. m 2) has a large posterior lobe added to the 

 quadricuspid principal part of the crown ; from which a fourth 

 fang is developed. In the more frugivorous bears of India and the 

 Indian Archipelago, the four premolars are commonly retained longer 

 than in the fiercer species of the Northern latitudes. M. de Blain- 

 ville has figured the jaws of the Ursus ornatus in which they are 

 all preserved in both jaws. I have seen the same condition in the 

 Ursus labiatus, the third small premolar above and the second and 

 third below having each two connate fangs : the fourth premolar 

 above presents three subequal obtuse tubercles in this species. In 

 the lower jaw as in the upper one, of all Bears, the first premolar 

 of the adult dentition (ib. fig. 2, p 1) cuts the gum, close to the 

 canine, before the deciduous teeth are shed; the second premolar 

 displaces the first deciduous molar ; the third displaces the second, 

 and the fourth the third. The fourth premolar (ib. figs. 5 & 6, ^ 4) 

 has a functionally developed crown, supported by two distinct fangs. 

 It is the only one of the four lower premolars retained in the 

 . dentition of the great extinct Ursus spelceus : the first premolar co- 

 exists with it in the Ursus priscus, as also commonly in the U. 

 maritimus and U. Arctos: in the latter I have seen likewise the 

 small third premolar with the adult dentition. The second lower 

 premolar is soon lost in the Bears of temperate and northern 

 latitudes, but is longer retained in the tropical species called ' Sun- 

 bears' {Helarctos, Horsefield). The first true molar (ib. fig. 5 & 6, 

 m 1) has a longer and narrower crown than the one above ; but, 



