522 CARNIVORES. 



development : its course is the same as that of the true molars, viz. 

 from before backwards, and is nearly parallel in point of time, but a 

 little anterior ; the first and generally the second true molars being in 

 place before the last premolar cuts the gum. I may further remark 

 that, when either series falls short of the typical number, which in the 

 placental Mammals, is four for the premolars and three for the true 

 molars, the absent teeth are from opposite ends of the two series, 

 being taken from the fore-part of the premolar, and from the back 

 part of the true molar series. 



No character is of less importance in the determination of the 

 essential nature and analogies of teeth than mere shape of the crown ; 

 peculiar modifications have obtained peculiar names ; the long, curved, 

 pointed incisors of the Elephant, and the similarly shaped canines 

 of the Walrus are called ' tusks,' or ' defenses :' the incisors of the 

 Beaver and canines of the Hippopotamus are compared to the 

 chisel, and called * dentes scalprarii', from the partial disposition of 

 the hard enamel, and the oblique bevelled cutting edge thence re- 

 sulting : we must not be surprised, therefore, to find a premolar in 

 one jaw and a true molar in the opposite jaw similarly modified 

 to cut flesh, and so placed in the alternate disposition of the teeth 

 of the ' Carcharodonta',(l) as to play in a greater or less proportion 

 upon each other, like the blades of scissors. In retaining, then, the 

 convenient and expressive term assigned by the Cuviers to these 

 sectorial teeth, it must, at the same time, be borne in mind that 

 they are not the analogous teeth in the two jaws, but, in these, respec- 

 tively belong to two naturally distinct categories of the molar teeth. 

 So, likewise, before we quit the Carnivorous series we find both 

 molars and premolars taking on as complete a tubercular structure 

 of the crown, and equally meriting the name of ' tuberculeuses' ;(2) and 

 it is in restricting the terms * sectorial' and * tubercular' to secondary 

 indications of the differences observable in the teeth composing the 

 two natural primary divisions of true molars and premolars, instead 

 of using them as characters for the primary division of the molar 

 series, that I chiefly dissent from the classification adopted in the 

 deservedly esteemed works of the Cuviers. 



(1) Aristotle's name for the modern * Carnivora.' 



(2) See JProcyon and other Subursi. 



