FAUNA ANTIQUA SIVALENSIS. 



Before entering upon these it will be convenient, for com- 

 parison, shortly to refer to the dental system of the Bears 

 generally. 



The number of the teeth varies more in the different species 

 of the Bears than in any other genus of the Camivora. The 

 incisors, canines, and the three posterior molars are constant 

 ill both jaws in all the species. The false molars are subject to 

 great variation. They are usually entirely wanting ' in the 

 upper jaw of the Ursus speloeus, or large fossil Bear of Europe, 

 while in other species they amount to three on either side. 

 The same variation holds in the lower jaw. In the TJrsus labi- 

 atus^ there are four false molars on each side, whUe in the Ursus 

 sjyelceus there is generally but one present : so that while the 

 number of teeth in the former extends in both jaws to 42, it 

 is commonly reduced in the latter to 30. This irregularity 

 in the number of false molars exists to a certain extent in 

 different individuals of the same species. In one skull of 

 the Ursus Tihetanus in our collection, which belonged to 

 an old animal, there are three false molars in the upper jaw 

 on each side ; while in the slnill of a younger individual with 

 unworn teeth there are but two. In another skull there are 

 no false molars on the left side, while there is one on the 

 right side, there being at the same time three false molars 

 on either side of the lower jaw. 



The characters depending on the form of the teeth are 

 very constant in the genus. The camassier or antepenulti- 

 mate molar, in the upper jaw, has but two lobes or points 

 along its length ; and the tubercle of its inner side is placed 

 opposite the rear lobe. The two rear molars are oblong, and 

 the last one has the additional development of a crenulated 

 spur or heel. The higher Camivora differ widely in these 

 characters from the Bears ; their carnassier teeth being three- 

 lobed, and the tubercle of the inside being placed forwards, 

 as in the Cats and Hysena, while the rear or tubercular 

 teeth are reduced in number and are rudimentary. 



We shall now proceed to the teeth of the fossil, which in 

 many respects deviate from the type of the genus, and 

 approximate that of the more perfect Camivora. Along with 

 the dimensions Ave annex those of the Ursus spelceus and 

 Ursus Tihetanus for comparison.^ 



' Cuvier, Ossemens Fossiles, torn. iv. 

 p. 351. 



2 This is constant in several skulls 

 in our collection. 



^ In tlie ' Ossemens Fossiles,' Cuvier 

 does not give the dimensions in width 

 of the teeth of the Ursm spelmm. We 



have to regret this omission, as one of 

 the most marked characters about our 

 fossil is the great width of the molars ; 

 and we have no other source to refer to 

 regarding the Ursus spelaus besides the 

 ' Ossemens Fossiles.' 



