HY^NA. 485 



than that of the second permanent premolar by which it is suc- 

 ceeded. The second deciduous molar is the sectorial tooth : the 

 inner tubercle is continued from the base of the middle lobe, and 

 thus resembles the permanent sectorial of the Glutton (Gulo) and 

 many -other Mustelida ; the deciduous tubercular molar is relatively 

 larger than in the adult Hycsna, and offers another feature of re- 

 semblance to the permanent dentition of the Glutton. It is also 

 worthy of remark that the exterior incisor of the upper jaw is not 

 only absolutely, but relatively smaller in the immature than in 

 the adult dentition of the Hyaena, giving another feature of resem- 

 blance to the more common type of dentition in the Carnivora. 



The first and second deciduous molars below (PI. 126, fig. 9) 

 have more compressed conical crowns than their successors : the third 

 deciduous molar (fig. 9, 3) is the sectorial tooth, and, again, as in 

 Gulo, has a better developed hinder tubercle than the permanent sec- 

 torial; it is not displaced by this tooth, but, as in other Carni- 

 vora, by a premolar (p. 4) of more simple character. The per- 

 manent sectorial (ml) is developed posteriorly and rises, like 

 other true molars, without displacing a deciduous predecessor. 



The permanent dentition of the Hycsna, as of other genera or 

 families of the Carnivora, assumes those characteristics which 

 adapt it for the peculiar food and habits of the adult and mark 

 the deviation from the common type, which always accompanies 

 the progress to maturity. The most characteristic modification of 

 this dentition is the great size and strength of the molars as 

 compared with the canines, and more especially the thick and 

 strong conical crowns of the second and third premolars in both 

 jaws, the base of the cone being belted by a strong ridge which 

 defends the subjacent gum.(l) This form of tooth is especially 

 adapted for gnawing and breaking bones, and the whole cranium 

 has its shape modified by the enormous development of the mus- 

 cles which work the jaws and teeth in this operation. (2) Adapted 



(1) An eminent Civil-Engineer, to whom I showed the jaw of a HyEena, observed that 

 the strong conical tooth, with its basal ridge was a perfect model of a hammer for 

 breaking stones for roads, 



(2) "The strength of the Hyaena's jaw is such that, in attacking a Dog, he begins 

 by biting off his leg at a single snap." Buckland, ' Reliquiae Diluvianae,' p. 23. 



