CANID/E. 475 



whence Cuvier has applied to this tooth the name of ' Dent car- 

 nassiere,' which I have rendered ' dens sectorius,' sectorial, or 

 scissor-tooth.(l) The compressed trenchant part of this tooth has 

 a sharp edge, more or less deeply cleft by one or two notches, 

 and with its divisions more or less pointed or produced in different 

 genera : this part of the crown of the sectorial tooth I call the 

 ' blade ;' it is usually combined with one or more basal tubercles. 

 The blade of the upper sectorial always plays upon the outside, 

 and a little in advance of the lower sectorial. The upper per- 

 manent sectorial succeeds and displaces a deciduous tubercular 

 molar in all Carnivora, and is, therefore, essentially a premolar 

 tooth : the lower sectorial comes up behind the deciduous series 

 and has no immediate predecessor, it is, therefore, a true molar 

 and the first of that class. By these criteria the sectorial teeth 

 may always be distinguished under every transitional variety of 

 form which they present in the Carnivorous series, from Ma- 

 chairodus in which the crown consists exclusively of the ' blade' 

 in both jaws, to Ursus in which it is wholly tubercular : the de- 

 velopment of the tubercle bearing an inverse relation to the 

 carnivorous propensities of the species. 



The leading modifications of the Carnivorous dentition will be 

 described as they are presented in the families typified respectively 

 by the Dog, the Civet, the Hyaena, the Tiger, the Stoat, the 

 Bear and the Seal. 



179. CanidcB. — The normal dental formula of the genus Canis 

 is : — 



3—3 1—1 4—4 2—2 . _ .„, - ^ _ ^ 1 o o V 



m. — : c. — \ pm. — ; m — : = 42. (PI. 125. fie:. I & 2.) 



3-3 ' 1-1 ' '^ 4—4 ' 3-3 ^ ° ^ 



The incisors (fig. 1) form a continuous series, describing the segment 

 of a circle in both jaws, and progressively increase in size from 

 the first to the third : the trenchant margin of the crown is divided 

 by two notches into a large middle and two small lateral lobes : 

 in the large external incisor the inner lobe is obsolete, the outer 



(1) ' Fleiscli-Zahn' of the German Naturalists; the term 'lacerator' is more applicable 

 to the canine than to the trenchant molar, to which it has been applied by some English 

 Authors. See Gardens and Menagerie of the Zoological Society, vol. i. p, 14. 



