514 



Vert'ehrata. 



lor(;molars may be termed inter digitating teeth (for they usually 

 interlock with those of the lower jaw), each has a compressed 

 triangular pointed crown, and one or two smaller cusps on the 

 posterior edge of the triangle, the anterior one being the smallest. 

 The fourth premolar (p*) , the sectorial or carnassial tooth, 

 is similarly compressed ; behind the apex there is a narrow notch in 

 the edge; and on the inner side a small tubercle: next to the 

 sectorial there follow two broad trituberculate teeth 

 {m} and m^), of which the anterior is the larger. The incisors and 

 canines of the lower jaw are like those of the upper ; there are, 

 however, seven molnrs (^4, wS), the first four resembling the 

 interdigitating teeth ; the fifth {m}), the largest tooth of the lower jaw, 

 is something like the fourth premolar of the upper, and is also 

 termed a sectorial; its anterior portion, which is situated below 

 the upper sectorial, is compressed and provided with two cusps, of 



which the posterior is 

 a little higher than 

 the anterior, whilst 

 the small posterior 

 portion of the tooth 

 is low and tubercu- 

 late. The last two 

 molars (m^ and m^) 

 are tritubercular, 

 like those of the upper 

 jaw, but are smaller. 



The modification 

 of the dental system 

 occurring in other 

 Oarnivora tends 



partly towards a 

 reduction of the 

 molar series proceed- 

 ing from both ends, 

 partly to a hyper- 

 trophy either of the 

 tubercular or of 

 the sectorial portion, 

 whilst the incisors 

 and canines as regards 

 number and form are 

 practically the same 

 To give examples of this ; in the Cat (Fig. 412), the dentition 



a 



Pig. 413. The teeth of the left half of the upper jaws 

 of: A Dog, B Bear, Marten, D Badger, E Viverid 

 (Berpestes), F Hysena, Cf Lion. The chief point to notice is 

 the great development of the tubercular portion (m' — m^) in 

 B and D, and the degeneration of this in E — G. — Orig. 



all. 



is degenerate as compared with that of the Dog ; of the six upper 

 molars of the latter, the first and the last have disappeared, and of 

 the four remaining, the first and the last are almost rudimentary ; as 



