396 A MANUAL OF DENTAL ANA TOM Y. 



true molar is a dwarfed tooth \vith but one cusp. Several 

 dental formula) have been assigned to the Hedgehog : there 

 is little room for difference of opinion as to the nomen- 

 clature of its upper teeth : though some authors (e.g.* 

 Professor Mivart) prefer to call the first premolar a canine. 

 But in the lower jaw some authors give i -c- pm _, 



others i _ c _ pm -, and others again, i - pm -. The 



last given seems the least artificial, and corresponds best 

 with the relations between the upper and lower teeth when 

 the mouth is closed. 



Rousseau describes the existence of twenty-four milk 



teeth, which he classifies thus : (i - dm -) ; that is to say, 



all the teeth in front of the true molars had deciduous pre- 

 decessors, but his grouping of them into incisors and molars 

 is quite arbitrary. 



The milk teeth are not shed and replaced until the 

 animal has attained to almost its full dimensions, and all 

 three true molars are in place. 



The teeth of the Hedgehog fairly represents sonic of the 

 features of Insectivorous dentitions, for the forcep-like in- 

 cisors, the stunted or non-developed canines, and the molars 

 bristling with pointed cusps, are common to very many 

 Insectivora. 



The Shrews have numerous sharply-pointed teeth, the 

 points interdigitating and fitting very closely together 

 when the mouth is shut. There is no tooth either in the 

 upper or lower jaw which is so elongated as to deserve the 

 name of canine ; but between the incisors and the true 

 molars are several small teeth which, by analogy, are called 

 prernolars. The true molars are not very different in 

 pattern from those of the mole (B in Fig. 176), and present 

 the W-contour so common in the molars of Insectivora. 



The most marked peculiarity in the dentition of the 



