H30 



CLASS MAMMALIA. 



connecting the present family with- the next. Ailurus is represented 

 at the present day by a single species from Nipal and the adjacent 

 regions. In common with the American members of the family it 

 is characterised by the second lower true molar being longer than 

 the first, and by the absence of a " carnassial " character in the 

 latter. The molars are, however, of an unusually complex character; 

 and the last one of the lower jaw presents a decided approximation 

 to the third molar of certain Ungulates. The only fossil that has 

 been referred to this genus is a fragment of a mandible with the last 

 true molar from the Red Crag of Suffolk. It is, however, advisable 

 to await further information before admitting this determination as 

 certain. 



Family Ursid^e. — Palaeontologically it appears advisable to in- 

 clude in this family not only the Bears, but also the Dogs (Cam'dte), 

 since the passage from one type to the other is so complete as to 

 render it impossible to draw any satisfactory distinction between 

 them. Although no precise definition of this family can be given, 

 the following points may be noticed. With the exception of the 



Fig. 1309. — Outer view of the right dentition of the Polar Bear (Ursus mar/timus). 

 Reduced, i, Incisors ; c, Canine ; pm, Premolars ; m, True molars. 



existing genus v£lurofius the skull has an alisphenoid canal. The 

 upper true molars are frequently two in number, but. they may be 

 reduced to one (Icticyon), or increased to three (Amfihicyon) or four 

 ( Otocyon) ; while the corresponding teeth of the lower jaw are nearly 

 always three in number, although they may be reduced to two, and 

 in Otocyon are augmented to four. The first upper true molar is 

 invariably placed behind the carnassial, and the latter generally has 

 two lobes. The upper true molars may have either oblong ( Ursus), 

 squared (Hyanarctus), or triangular crowns ; and the talon of the 



