CLASSIFICATION OF MOLARS. 521 



molar series, the typical Felines have not two, but three premolars 

 on each side of the upper jaw, and two premolars, instead of one, 

 en each side of the lower jaw. I have come to the conclusion, 

 therefore, after a long and patient series of researches upon both 

 the deciduous and permanent dentition of the Mammaha, that a 

 * molaire principale' does not exist in nature, that its characters 

 as defined by M. de Blainville are artificial, and that they utterly 

 fail, or mislead, in their application to a philosophic determination 

 of the analogous teeth in the diff"erent genera of placental and 

 terrestrial Mammalia. 



Having premised thus much in explanation of the grounds 

 which have prevented my adopting the dental formulae assigned to 

 the genera of Mammalia, not only by M. de Blainville, but by the 

 Cuviers, I have only to add an explanation of the principles of 

 the formulae substituted for them in the present work. As respects 

 the molar teeth, I believe my classification to be founded on a more 

 important, a more constant, and therefore a more natural character 

 than those of ' form,' ' size,' or * relative position.' According to 

 the law of development the series of true molars begins with that 

 tooth which rises into place behind the last of the deciduous series 

 and includes all behind it ; all the permanent molars in front of this 

 series are premolars. I have already exemplified the application of 

 this law to the determination of the analogous true-molar teeth in 

 the Lion and Man, and I may observe that it is equally applicable 

 to the identification of every tooth in the molar series. Accord- 

 ing to it, the first upper true molar tooth in the Human Subject, 

 (' principale' of M. de Blainville), is the analogue of the last, or 

 tubercular molar in the upper jaw of the Lion; the first lower 

 true molar tooth in Man answers to the lower sectorial tooth 

 in the Lion ; the upper sectorial in the Lion is essentially the 

 same tooth as the second superior bicuspid in Man ; the second 

 upper premolar of the Lion answers to the first upper bicuspis in 

 Man; the first small premolar in the Lion has no analogue in the 

 Human dentition ; the two premolars in the lower jaw of the 

 Lion correspond with the two inferior bicuspids in Man. 



The natural character of the premolars as a distinct subdivision ot 

 the molar series is shown by a certain independence in their time of 



