276 THE MAMMALIA. 



was able to establish in these animals, justifies 

 the supposition that this small piece will disappear 

 later, in the same manner as has happened 

 previously to the one that existed in front of it (p } ), 

 and had previously happened to the tuberculate 

 tooth (?ft 2 ). The genus Felis herewith appears upon 

 the scenes. 



The concentration of the dentition did not re- 

 main stationary at the stage acquired by the cats, 



3 1 



p - , m - ; the highest degree of specialisation was 



attained by the so-called Sabre-toothed tiger (Ma- 

 chairodus) with the dental formula : 



.31 20 



t -, c _, p ~ m- 



3 12 1 



with 26 teeth against 30 in the cats. Machairodus, 

 an animal somewhat the size of a tiger, possessed 

 in its upper jaw a powerful sabre- shaped canine 

 tooth which projected from the mouth downwards 

 extending beyond the lower jaw. This lower jaw 

 shows an indentation obviously produced by the 

 pressure of the huge upper canine teeth as they 

 became more and more developed and endeavoured 

 to make room for themselves. The cause of the 

 dying out of this most definite of all the Carnivora 

 of the period, has been attributed to the extra- 



