80 



NATURAL HISTORY. 



furnished with a set of tools which, when worked by such mighty power, are simply irresistible. 

 The large grinding-teeth, instead of the scissor-blade form they have in the Cats, have great conical 

 crowns, the base of the cone being belted by a strong ridge which defends the subjacent gum (see 

 figure on preceding page). One has only to look at these teeth to see their perfect adaptation to their 

 purpose. Sir Richard Owen remarks, " An eminent civil engineer, to whom 1 showed the jaw of 

 a Hysena, observed that the strong conical tooth, with its basal ridge, was a perfect model of a hammer 

 for breaking stones for roads." 



The canines of the Hysena are proportionally much smaller than in the Felidce, and the 

 outermost incisor that nearest the canine is much larger than in the Cats, so that it approaches 

 towards the canine in size. This, as we shall see, is even more the case in the Dog. 



Then, the number of the teeth is different ; the Hysena is a less specialised animal than the Cats, 

 that is, departs less from the average structure of a Mammal, and, in correspondence with this, we find 



SKELETON OF HYAENA. 



that its jaws are longer and its teeth more numerous ; it has, in fact, one more premolar, or false grind* 

 on each side of each jaw, bringing the total nnmber of teeth to thirty-four, instead of thir 

 (See p. 13.)* 



In speaking of the Cat family, we mentioned that the characters of the floor of the skull, and 

 particularly of the swollen, bulb-like bulla tympani, were of great importance in determining the 

 position of an animal in the series. Now this bulla in the Hysena is large and rounded, as in Cats, but 

 differs in the fact that it is not divided by a bony partition into two compartments. The external 

 opening of the cavity, too, is quite flush with its outer wall, and the clamp of bone (see figures on 

 pp. 11 and 79) is quite close to its hinder wall. 



In these characters, as well as in certain matters of internal structure, such as the presence of a 

 small caecum, or " blind-gut," the Hyaenas approach to the Cats and Civets, being connected with the 

 latter group by the curious Aard-Wolf. In other respects they approach the Dog family, their nearest 

 ally in that group being the Cape Hunting Dog.f 



* The dental formula is incisors, |^j, canines, ^j, premolars, , molars, ^EJ, = 34. 

 t Lycaon. 



