260 THE MAMMALIA. 



ship between the species which ranged separated 

 over half of the earth's surface, or they point to 

 the different origin of those which live almost 

 within the same range of distribution. The 

 certainty with which a palaeontologist works by 

 making use of means which appear absolutely 

 valueless to an unscientific person can be appre- 

 ciated only by those who have acquired at least 

 some knowledge of the way in which the work is 

 accomplished. This again shows what little weight 

 can be placed in the perpetual assertions of un- 

 scientific persons, that the followers of the theory 

 of descent are not in the position to prove the 

 transformation of species. 



Everyone knows that the dentition of the fox 

 (Canis vulpes) consists of very differently formed 

 teeth (Fig. 48), which, however, agree in so far 

 that the crowns show an unbroken covering of 

 enamel ; in this the molars, more especially, differ 

 strikingly from those of the Hoofed Animals and 

 many of the Eodents, where the crowns have com- 

 plicated folds of enamel. The dental formula 



is : i -, c -, pin .-, m - . For our purpose here 

 o 1 4 o 



it is the molars almost exclusively that come into 



4 2 



consideration, hence : - . Thus the genus Dog 

 4 o 



