ANATOMY OF VERTEBRATES. 



But the inconvenience of names indicative of such specialties 

 ' of form will he very ohvious when the term ' tuberculeuses ' 

 comes to be applied to the three hindmost teeth in the Hycenodon 

 (fig. 266), which teeth answer to the broad crushing teeth, m i, 

 in 2, and m 3, in the bear and some other existing Carnivora. 

 The analogous term ( molar ' having a less direct or descriptive 

 meaning, is therefore so much the better, as the requisite arbitrary 

 name of a determinate species of teeth. 



Had Cuvier been guided in his determinations of the teeth by 

 their mutual opposition in the closed mouth, and had studied 

 them with this view in the Carnivora with the dentition most 

 nearly approaching to the typical formula, viz. the Bear, he could 

 then have seen that the three small and inconstant lower pre- 

 molars, p i, p 2, p 3, were the homotypes of the three small and 

 similarly inconstant premolars above ; that the fourth false molar, 

 p 4 below, which, as he observes, ' alone has the normal form,' l 

 was truly the homotype of the tooth above, p 4, which he found 

 himself compelled to reject from the class of s fausses molaires,' 

 notwithstanding it presented their normal form ; that the tuber- 

 cular tooth, m i, which he calls ( carnassiere ' in the lower jaw, 

 was the veritable homotype of his first ( molaire tuberculeuse ' 

 above, m i, and that the tooth in the inferior series, which 

 had no answerable one above, was his second ( tuberculeuse,' 

 m 3, in the present work. The true second tubercular above, 

 m 2, is, however, so much developed in the Bear as to oppose 

 both m 2 and m 3 in the lower jaw, and it might seem to include 

 the homotypes of both those teeth coalesced. One sees with an 

 interest such as only these homological researches could excite, 

 that they were distinctly developed in the ancient Amphicyon^ 

 fig. 267, which accordingly presents the typical formula. 



Thus the study of the relative position of the teeth of the Bear 

 might have led to the recognition of their real nature and homo- 

 logies, and have helped to raise the mask of the extreme formal 

 modifications, by which they are adapted to the habits of the 

 more blood-thirsty Carnivora. But the truth is plainly revealed 

 when we come to trace the course of development and succession 

 of these teeth. As the question only concerns the molar series, 

 the remarks will be confined to those teeth. In the jaws of the 

 young Bear, fig. 263, the first premolar is the only one of the 

 permanent series in place ; the other grinders in use are the 

 deciduous molars, d 2, d 3, and d 4 ; d 2 will be displaced by p 2, 

 d 3 by p 3, and d 4 by the tooth p 4, which, notwithstanding its 



1 cxxi". p. 1H. 



